US20140175584A1 - Magnetic field sensor and method of fabricating a magnetic field sensor having a plurality of vertical hall elements arranged in at least a portion of a polygonal shape - Google Patents
Magnetic field sensor and method of fabricating a magnetic field sensor having a plurality of vertical hall elements arranged in at least a portion of a polygonal shape Download PDFInfo
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- US20140175584A1 US20140175584A1 US13/724,170 US201213724170A US2014175584A1 US 20140175584 A1 US20140175584 A1 US 20140175584A1 US 201213724170 A US201213724170 A US 201213724170A US 2014175584 A1 US2014175584 A1 US 2014175584A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/30—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring angles or tapers; for testing the alignment of axes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/82—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by variation of the magnetic field applied to the device
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
- G01R33/07—Hall effect devices
- G01R33/077—Vertical Hall-effect devices
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/0023—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration
Definitions
- This invention relates generally to magnetic field sensors and related fabrication techniques, and, more particularly, to a magnetic field sensor and corresponding fabrication technique having a plurality of vertical Hall elements arranged in at least a portion of a polygonal pattern and also having an electronic circuit coupled to the plurality of vertical Hall elements.
- Planar Hall elements and vertical Hall elements are known types of magnetic field sensing elements that can be used in magnetic field sensors.
- a planar Hall element tends to be responsive to magnetic field perpendicular to a surface of a substrate on which the planar Hall element is formed.
- a vertical Hall element tends to be responsive to magnetic field parallel to a surface of a substrate on which the vertical Hall element is formed.
- CVH circular vertical Hall
- PCT Patent Application No. PCT/EP2008/056517 entitled “Magnetic Field Sensor for Measuring Direction of a Magnetic Field in a Plane,” filed May 28, 2008, and published in the English language as PCT Publication No. WO 2008/145662, which application and publication thereof are incorporated by reference herein in their entirety.
- the CVH sensing element is a circular arrangement of vertical Hall elements arranged over a common circular implant region in a substrate.
- the CVH sensing element can be used to sense a direction (and optionally a strength) of a magnetic field in a plane of the substrate.
- Various parameters characterize the performance of magnetic field sensing elements. These parameters include sensitivity, which is a change in an output signal of a magnetic field sensing element in response to a change of magnetic field experienced by the magnetic sensing element, and linearity, which is a degree to which the output signal of the magnetic field sensing element varies in direct proportion to the magnetic field. These parameters also include an offset, which is characterized by an output signal from the magnetic field sensing element not representative of a zero magnetic field when the magnetic field sensing element experiences a zero magnetic field.
- Another parameter that can characterize the performance of a CVH sensing element is the speed with which output signals from vertical Hall elements within the CVH sensing element can be sampled, and thus, the speed with which a direction of a magnetic field can be identified.
- Yet another parameter that can characterize the performance of a CVH sensing element is the resolution (e.g., angular step size) of the direction of the magnetic field that can be reported by the CVH sensing element.
- the CVH sensing element is operable, with associated circuits, to provide an output signal representative of an angle of a direction of a magnetic field. Therefore, as described below, if a magnet is disposed upon or otherwise coupled to a so-called “target object,” for example, a camshaft in an engine, the CVH sensing element can be used to provide an output signal representative of an angle of rotation, and/or a rotation speed, of the target object.
- target object for example, a camshaft in an engine
- a magnetic field sensor that uses a CVH sensing element may have a limit as to how rapidly the magnetic field sensor can identify the direction of a magnetic field, i.e., a rotation angle or rotation speed of a target object.
- the magnetic field sensor may provide an angular resolution that is too low (too large an angle step size). In general, it may be possible to provide a higher resolution, but at the expense of more time.
- a magnetic field sensing element (or, more generally, a plurality of magnetic field sensing elements) that can be used to generate an output signal more rapidly indicative of an angle of a magnetic field than a CVH sensing element.
- the present invention provides a magnetic field sensing element (or, more generally, a plurality of magnetic field sensing elements) that can be used to generate an output signal more rapidly indicative of an angle of a magnetic field than a CVH sensing element.
- a magnetic field sensor in accordance with one aspect of the present invention, includes a semiconductor substrate having a planar surface.
- the magnetic field sensor also includes a plurality of primary vertical Hall elements disposed on the planar surface.
- Each one of the plurality of primary vertical Hall elements includes a respective plurality of primary vertical Hall element contacts arranged in a respective line.
- the lines of primary vertical Hall element contacts are arranged in a pattern representative of at least a portion of a polygonal shape.
- the plurality of primary vertical Hall elements includes a primary vertical Hall element having a respective line of vertical Hall element contacts not parallel to a line of vertical Hall element contacts of another one of the plurality of primary vertical Hall elements.
- Each one of the plurality of primary vertical Hall elements is configured to generate a respective magnetic field signal indicative of a projected component of a magnetic field projected upon the plane of the planar surface relative to an angular position of the respective vertical Hall element.
- the magnetic field sensor also includes an electronic circuit disposed on the planar surface and coupled to each one of the plurality of primary vertical Hall elements. The electronic circuit is configured to generate an output signal indicative of an angle of the projected component of the magnetic field.
- the magnetic field sensor also includes a plurality of secondary vertical Hall elements disposed on the planar surface.
- Each one of the secondary vertical Hall elements includes a respective plurality of secondary vertical Hall element contacts arranged in a respective line.
- Each one of the plurality of secondary vertical Hall elements is arranged in a respective group with a respective one of the plurality of primary vertical Hall elements.
- Each line of secondary vertical Hall element contacts is geometrically arranged at a predetermined angle with a respective line of primary vertical Hall element contacts to form a plurality of parallel groups of vertical Hall elements.
- a method of fabricating a magnetic field sensor includes providing a semiconductor substrate having a planar surface. The method also includes forming, on the planar surface, a plurality of primary vertical Hall elements. Each one of the plurality of primary vertical Hall elements comprises a respective plurality of vertical Hall element contacts arranged in a respective line of primary vertical Hall element contacts. The lines of primary vertical Hall element contacts are arranged in a pattern representative of at least a portion a polygonal shape.
- the plurality of primary vertical Hall elements includes a primary vertical Hall element having a respective line of vertical Hall element contacts not parallel to a line of vertical Hall element contacts of another one of the plurality of primary vertical Hall elements.
- Each one of the plurality of primary vertical Hall elements is configured to generate a respective magnetic field signal indicative of a projected component of a magnetic field projected upon the plane of the planar surface relative to an angular position of the respective vertical Hall element.
- the method also includes forming, on the semiconductor substrate, an electronic circuit coupled to each one of the plurality of primary vertical Hall elements. The electronic circuit is configured to generate an output signal representative of an angle of the projected component of the magnetic field.
- the method also includes forming, on the planar surface, a plurality of secondary vertical Hall elements.
- Each one of the secondary vertical Hall elements includes a respective plurality of secondary vertical Hall element contacts arranged in a respective line.
- Each one of the plurality of secondary vertical Hall elements is arranged in a respective group with a respective one of the plurality of primary vertical Hall elements.
- Each line of secondary vertical Hall element contacts is geometrically arranged at a predetermined angle with a respective line of primary vertical Hall element contacts to form a plurality of parallel groups of vertical Hall elements.
- a magnetic field sensor in accordance with another aspect of the present invention, includes a semiconductor substrate having a planar surface.
- the magnetic field sensor also includes a plurality of magnetic field sensing elements disposed on the planar surface.
- the plurality of magnetic field sensing elements has a respective plurality of major response axes, each major response axis parallel to the major surface.
- the plurality of major response axes is arranged in a pattern representative of at least a portion of a polygonal shape.
- the plurality of magnetic field sensing elements includes a primary vertical Hall element having a major response axis not parallel to major response axis of another one of the plurality of magnetic field sensing elements.
- Each one of the plurality of magnetic field sensing elements is configured to generate a respective magnetic field signal indicative of a projected component of a magnetic field projected upon the plane of the planar surface relative to an angular position of the response axis of the respective magnetic field sensing element.
- the magnetic field sensor also includes an electronic circuit disposed on the planar surface and coupled to each one of the plurality of magnetic field sensing elements. The electronic circuit is configured to generate an output signal indicative of an angle of the projected component of the magnetic field.
- the plurality of magnetic field sensing elements comprises a plurality of magnetoresistance elements.
- a method of fabricating a magnetic field sensor includes providing a semiconductor substrate having a planar surface. The method also includes forming, on the planar surface, a plurality of magnetic field sensing elements having a respective plurality of major response axes, each major response axis parallel to the major surface. The plurality of major response axes is arranged in a pattern representative of at least a portion of a polygonal shape.
- the plurality of magnetic field sensing elements includes a primary vertical Hall element having a major response axis not parallel to major response axis of another one of the plurality of magnetic field sensing elements.
- Each one of the plurality of magnetic field sensing elements is configured to generate a respective magnetic field signal indicative of a projected component of a magnetic field projected upon the plane of the planar surface relative to an angular position of the response axis of the respective magnetic field sensing element.
- the method also includes forming, on the semiconductor substrate, an electronic circuit coupled to each one of the plurality of magnetic field sensing elements. The electronic circuit is configured to generate an output signal indicative of an angle of the projected component of the magnetic field.
- the plurality of magnetic field sensing elements comprises a plurality of magnetoresistance elements.
- FIG. 1 is a pictorial showing a circular vertical Hall (CVH) sensing element having a plurality of vertical Hall elements arranged in a circle over a common implant region in a substrate and a two pole ring magnet disposed close to the CVH sensing element;
- CVH circular vertical Hall
- FIG. 2 is a graph showing an output signal as may be generated by the CVH sensing element of FIG. 1 ;
- FIG. 3 is a block diagram showing an electronic circuit using a CVH sensing element to determine a direction of a sensed magnetic field
- FIG. 4 is a pictorial of an exemplary magnetic field sensor having six vertical Hall elements arranged in a hexagonal pattern over a common implant region in a substrate;
- FIG. 5 is a pictorial of another exemplary magnetic field sensor having six vertical Hall elements arranged in a hexagonal pattern, each arranged over separate implant regions;
- FIG. 6 is a pictorial of another exemplary magnetic field sensor having six primary vertical Hall elements arranged in a hexagonal pattern and also having six secondary vertical Hall elements arranged in a hexagonal pattern;
- FIG. 7 is a pictorial of another exemplary magnetic field sensor having three primary vertical Hall elements arranged a portion of (here half of) a hexagonal pattern and also having three secondary vertical Hall elements arranged in a half of a hexagonal pattern;
- FIG. 7A is a pictorial of another exemplary magnetic field sensor having three primary vertical Hall elements arranged in a portion of (here half of) of a hexagonal pattern and also having three secondary vertical Hall elements arranged in a half of a hexagonal pattern;
- FIG. 8 is a pictorial of another exemplary magnetic field sensor having three vertical Hall elements arranged a portion of (here half of) of a hexagonal pattern;
- FIG. 8A is a pictorial of another exemplary magnetic field sensor having three vertical Hall elements arranged a portion of (here half of) of a hexagonal pattern;
- FIG. 9 is a graph showing output signal that can be generated by the vertical Hall elements of the arrangement of FIGS. 4 and 5 .
- magnetic field sensing element is used to describe a variety of electronic elements that can sense a magnetic field.
- the magnetic field sensing elements can be, but are not limited to, Hall Effect elements, magnetoresistance elements, or magnetotransistors.
- Hall Effect elements for example, a planar Hall element, a vertical Hall element, and a circular Hall element.
- GMR giant magnetoresistance
- AMR anisotropic magnetoresistance element
- TMR tunneling magnetoresistance
- InSb Indium antimonide
- MTJ magnetic tunnel junction
- the term “sensor” is used to describe a circuit or assembly that includes a sensing element and other components.
- the term “magnetic field sensor” is used to describe a circuit or assembly that includes a magnetic field sensing element and electronics coupled to the magnetic field sensing element.
- some of the above-described magnetic field sensing elements tend to have an axis of maximum sensitivity parallel to a substrate that supports the magnetic field sensing element, and others of the above-described magnetic field sensing elements tend to have an axis of maximum sensitivity perpendicular to a substrate that supports the magnetic field sensing element.
- planar Hall elements tend to have axes of sensitivity perpendicular to a substrate
- magnetoresistance elements and vertical Hall elements including circular vertical Hall (CVH) sensing elements
- Magnetic field sensors are used in a variety of applications, including, but not limited to, an angle sensor that senses an angle of a direction of a magnetic field, a current sensor that senses a magnetic field generated by a current carried by a current-carrying conductor, a magnetic switch that senses the proximity of a ferromagnetic object, a rotation detector that senses passing ferromagnetic articles, for example, magnetic domains of a ring magnet, and a magnetic field sensor that senses a magnetic field density of a magnetic field.
- an angle sensor that senses an angle of a direction of a magnetic field
- a current sensor that senses a magnetic field generated by a current carried by a current-carrying conductor
- a magnetic switch that senses the proximity of a ferromagnetic object
- a rotation detector that senses passing ferromagnetic articles, for example, magnetic domains of a ring magnet
- a magnetic field sensor that senses a magnetic field density of a magnetic field.
- the vertical Hall element contacts of one or more of the vertical Hall elements can be arranged in respective arcs.
- the term “line” is used to describe either a straight line or a curved line.
- a circular vertical Hall (CVH) sensing element 12 includes a circular implant region 18 having a plurality of vertical Hall elements disposed thereon, of which a vertical Hall element 12 a is but one example.
- Each vertical Hall element has a plurality of Hall element contacts (e.g., four or five contacts), of which a vertical Hall element contact 12 aa is but one example.
- a particular vertical Hall element (e.g., 12 a ) within the CVH sensing element 12 which, for example, can have five adjacent contacts, can share some, for example, four, of the five contacts with a next vertical Hall element (e.g., 12 b ).
- a next vertical Hall element can be shifted by one contact from a prior vertical Hall element.
- the number of vertical Hall elements is equal to the number of vertical Hall element contacts, e.g., 32.
- a next vertical Hall element can be shifted by more than one contact from the prior vertical Hall element, in which case, there are fewer vertical Hall elements than there are vertical Hall element contacts in the CVH sensing element.
- a center of a vertical Hall element 0 is positioned along an x-axis 20 and a center of vertical Hall element 8 is positioned along a y-axis 22 .
- a CVH can have more than or fewer than thirty-two vertical Hall elements and more than or fewer than thirty-two vertical Hall element contacts.
- a circular magnet 14 having a south side 14 a and a north side 14 b can be disposed over the CVH 12 .
- the circular magnet 14 tends to generate a magnetic field 16 having a direction from the north side 14 a to the south side 14 b , here shown to be pointed to a direction of about forty-five degrees relative to x-axis 20 .
- Other magnets having other shapes and configurations are possible.
- the circular magnet 14 is mechanically coupled to a rotating object (a target object), for example, an automobile crank shaft or an automobile camshaft, and is subject to rotation relative to the CVH sensing element 12 .
- a rotating object for example, an automobile crank shaft or an automobile camshaft
- the CVH sensing element 12 in combination with an electronic circuit described below can generate a signal related to the angle of rotation of the magnet 14 .
- the CVH sensing element 12 can be disposed upon a substrate 26 , for example, a silicon substrate, along with other electronics (not shown).
- a graph 50 has a horizontal axis with a scale in units of CVH vertical Hall element position, n, around a CVH sensing element, for example, the CVH sensing element 12 of FIG. 1 .
- the graph 50 also has a vertical axis with a scale in amplitude in units of millivolts.
- the graph 50 includes a signal 52 representative of output signal levels from the plurality of vertical Hall elements of the CVH taken sequentially with the magnetic field of FIG. 1 stationary and pointing in a direction of forty-five degrees.
- vertical Hall element 0 is centered along the x-axis 20 and vertical Hall element 8 is centered along the y-axis 22 .
- the exemplary CVH sensing element 12 there are thirty-two vertical Hall element contacts and a corresponding thirty-two vertical Hall elements, each vertical Hall element having a plurality of vertical Hall element contacts, for example, five contacts.
- a maximum positive signal is achieved from a vertical Hall element centered at position 4 , which is aligned with the magnetic field 16 of FIG. 1 , such that a line drawn between the vertical Hall element contacts (e.g., five contacts) of the vertical Hall element at position 4 is perpendicular to the magnetic field.
- a maximum negative signal is achieved from a vertical Hall element centered at position 20 , which is also aligned with the magnetic field 16 of FIG. 1 , such that a line drawn between the vertical Hall element contacts (e.g., five contacts) of the vertical Hall element at position 20 is also perpendicular to the magnetic field.
- a sine wave 54 is provided to more clearly show the ideal behavior of the signal 52 .
- the signal 52 has variations due to vertical Hall element offsets, which tend to somewhat randomly cause element output signals to be too high or too low relative to the sine wave 54 , in accordance with offset errors for each element.
- the offset signal errors are undesirable.
- the offset errors can be reduced by “chopping” each vertical Hall element. Chopping will be understood to be a process by which vertical Hall element contacts of each vertical Hall element are driven in different configurations and signals are received from different ones of the vertical Hall element contacts of each vertical Hall element to generate a plurality of output signals from each vertical Hall element.
- the plurality of signals can be arithmetically processed (e.g., summed or otherwise averaged) resulting in a signal with less offset.
- groups of contacts of each vertical Hall element can be used in a chopped arrangement to generate chopped output signals from each vertical Hall element. Thereafter, a new group of adjacent vertical Hall element contacts can be selected (i.e., a new vertical Hall element), which can be offset by one or more elements from the prior group. The new group can be used in the chopped arrangement to generate another chopped output signal from the next group, and so on.
- Each step of the signal 52 can be representative of a chopped output signal from one respective group of vertical Hall element contacts, i.e., from one respective vertical Hall element. However, in other embodiments, no chopping is performed and each step of the signal 52 is representative of an unchopped output signal from one respective group of vertical Hall element contacts, i.e., from one respective vertical Hall element.
- the graph 52 is representative of a CVH output signal with or without the above-described grouping and chopping of vertical Hall elements.
- a phase of the signal 52 (e.g., a phase of the signal 54 ) can be found and can be used to identify the pointing direction of the magnetic field 16 of FIG. 1 relative to the CVH sensing element 12 .
- a magnetic field sensor 70 includes a sensing portion 71 .
- the sensing portion 71 can include a CVH sensing element 72 having a plurality of CVH sensing element contacts, e.g., a CVH sensing element contact 73 .
- a CVH sensing element contact 73 there are thirty-two vertical Hall elements in the CVH sensing element 72 and a corresponding thirty-two CVH sensing element contacts.
- the CVH sensing element 72 can have more than or fewer than thirty-two vertical Hall elements and/or more than or fewer than thirty-two vertical Hall element contacts.
- a magnet (not shown) can be disposed proximate to the CVH sensing element 72 , and can be coupled to a target object (not shown).
- the magnet can be the same as or similar to the magnet 14 of FIG. 1
- the CVH sensing element 72 can have a plurality of vertical Hall elements, each vertical Hall element comprising a group of vertical Hall element contacts (e.g., five vertical Hall element contacts), of which the vertical Hall element contact 73 is but one example.
- a switching circuit 74 can provide sequential CVH differential output signals 72 a , 72 b from the CVH sensing element 72 .
- the CVH differential output signal 72 a , 72 b is comprised of sequential output signals taken one-at-a-time around the CVH sensing element 72 , wherein each output signal is generated on a separate signal path and switched by the switching circuit 74 into the path of the differential output signal 72 a , 72 b .
- the signal 52 of FIG. 2 can be representative of the differential signal 72 a , 72 b .
- a vertical Hall element position i.e., a position of a group of vertical Hall element contacts that form a vertical Hall element
- the number of vertical Hall elements (each comprising a group of vertical Hall element contacts) in the CVH sensing element 72 is equal to the total number of sensing element positions, N.
- the CVH differential output signal 72 a , 72 b can be comprised of sequential output signals, wherein the CVH differential output signal 72 a , 72 b is associated with respective ones of the vertical Hall elements in the CVH sensing element 72 as the switching circuit 74 steps around the vertical Hall elements of the CVH sensing element 72 by increments of one, and N equals the number of vertical Hall elements in the CVH sensing element 72 .
- the increments can be by greater than one vertical Hall element, in which case N is less than the number of vertical Hall elements in the CVH sensing element 72 .
- N the number of vertical Hall elements in the CVH sensing element 72
- the increments of vertical Hall element positions, n can be greater than one vertical Hall element contact.
- another switching circuit 76 can provide the above-described “chopping” of groups of the vertical Hall elements within the CVH sensing element 72 .
- Chopping will be understood to be an arrangement in which a group of vertical Hall element contacts, for example, five vertical Hall element contacts that form one vertical Hall element, are driven with current sources 86 in a plurality of different connection configurations, and signals are received from the group of vertical Hall element contacts in corresponding different configurations to generate the CVH differential output signal 72 a , 72 b .
- n there can be a plurality of sequential output signals during the chopping, and then the group increments to a new group, for example, by an increment of one vertical Hall element contact.
- the sensing portion 71 can also include current sources 86 configured to drive the CVH sensing element 72 . While current sources 86 are shown, in other embodiments, the current sources 86 can be replaced by voltage sources.
- the magnetic field sensor 70 includes an oscillator 78 that provides clock signals 78 a , 78 b , 78 c , which can have the same or different frequencies.
- a divider 80 is coupled to receive the clock signal 78 a and configured to generate a divided clock signal 80 a .
- a switch control circuit 82 is coupled to receive the divided clock signal 80 a and configured to generate switch control signals 82 a , which are received by the switching circuits 74 , 76 to control the sequencing around the CVH sensing element 72 , and optionally, to control the chopping of groups of vertical Hall elements within the CVH sensing element 72 in ways described above.
- the magnetic field sensor 70 can include a divider 88 coupled to receive the clock signal 78 c and configured to generate a divided clock signal 88 a , also referred to herein as an “angle update clock” signal.
- the magnetic field sensor 70 also includes an x-y direction component circuit 90 .
- the x-y direction component circuit 90 can include an amplifier 92 coupled to receive the CVH differential output signals 72 a , 72 b .
- the amplifier 92 is configured to generate an amplified signal 92 a .
- a bandpass filter 94 is coupled to receive the amplified signal 92 a and configured to generate a filtered signal 94 a .
- a comparator 96 with or without hysteresis, is configured to receive the filtered signal 94 a .
- the comparator 96 is also coupled to receive a threshold signal 120 .
- the comparator 96 is configured to generate a thresholded signal 96 a generated by comparison of the filtered signal 94 a with the threshold signal 120 .
- the x-y direction component circuit 90 also includes an amplifier 114 coupled to receive the divided clock signal 88 a .
- the amplifier 114 is configured to generate an amplified signal 114 a.
- a bandpass filter 116 is coupled to receive the amplified signal 114 a and configured to generate a filtered signal 116 a .
- a comparator 118 is coupled to receive the filtered signal 116 a .
- the comparator 118 is also coupled to receive a threshold signal 122 .
- the comparator 118 is configured to generate a thresholded signal 118 a by comparison of the filtered signal 116 a with the threshold signal 122 .
- the bandpass filters 94 , 116 can have center frequencies equal to 1/T, where T is the time that it takes to sample all of the vertical Hall elements within the CVH sensing element 72 .
- the amplifier 114 , the bandpass filter 116 , and the comparator 118 provide a delay of the divided clock signal 88 a in order to match a delay of the circuit channel comprised of the amplifier 92 , the bandpass filter 94 , and the comparator 96 .
- the matched delays provide phase matching, in particular, during temperature excursions of the magnetic field sensor 70 .
- a counter 98 can be coupled to receive the thresholded signal 96 a at an enable input, to receive the clock signal 78 b at a clock input, and to receive the thresholded signal 118 a at a reset input.
- the counter 98 is configured to generate a phase signal 98 a having a count representative of a phase difference between the thresholded signal 96 a and the thresholded signal 118 a.
- the phase shift signal 98 a is received by a latch 100 that is latched upon an edge of the divided clock signal 88 a .
- the latch 100 is configured to generate a latched signal 100 a , also referred to herein as an “x-y angle signal.”
- the latched signal 100 a is a multi-bit digital signal that has a value representative of a direction of an angle of the magnetic field experience by the CVH sensing element 72 , and thus, an angle of the magnet and target object.
- the signal 52 of FIG. 2 is representative of the latched signal 100 a.
- the magnetic field sensor 70 can also include a filter 102 coupled to receive the latched signal 100 a and configured to generate a filtered signal 102 a .
- the signal 54 of FIG. 2 is representative of the filtered signal 102 a.
- the clock signals 78 a , 78 b , 78 c each have a frequency of about 30 MHz
- the divided clock signal 80 a has a frequency of about 8 MHz
- the angle update clock signal 88 a has a frequency of about 30 kHz.
- the initial frequencies can be higher or lower than these frequencies
- an update rate of the x-y angle signal 100 a occurs at a rate equivalent to a rate at which all of the vertical Hall elements within the CVH sensing element 72 are collectively sampled.
- An exemplary rate is described below in conjunction with FIG. 4
- a magnetic field sensor 100 includes a semiconductor substrate 101 having a planar surface 101 a .
- the magnetic field sensor 100 also includes a plurality of vertical Hall elements 103 , individually 102 a , 102 b , 102 c , 102 d , 102 e , 102 f , disposed on the planar surface 101 a .
- each one of the vertical Hall elements includes a respective plurality of vertical Hall element contacts like vertical Hall element contacts 106 a , 106 b , 106 c , 106 d , 106 e .
- Each plurality of vertical Hall element contacts is arranged in a respective line.
- the lines of vertical Hall element contacts are arranged in a pattern representative of a polygonal shape, here a hexagon.
- Each one of the plurality of vertical Hall elements 102 a , 102 b , 102 c , 102 d , 102 e , 102 f is configured to generate a respective magnetic field signal responsive to of an angle of a projected component 109 of a magnetic field projected upon the plane of the planar surface 101 a relative to an angular position of the respective vertical Hall element.
- a magnet is not shown, but can be the same as or signal to the magnet 18 of FIG. 1 and disposed proximate to the plurality of magnetic field sensing elements 103 .
- sequential output signals from the plurality of vertical Hall elements 103 are indicated as a signal 103 a .
- the signal 103 a can be similar to the differential signal 72 a , 72 b of FIG. 3 .
- the vertical Hall element 102 a is operated by driving a current into selected ones, e.g., two, of the vertical Hall element contacts 106 a , 106 b , 106 d , 106 d , 106 e , in which case, an output signal is generated at the non-selected ones, e.g., three, of the vertical Hall element contacts.
- a chopping process used to reduce the effect of any offset voltage of the vertical Hall element 102 a , the selection of vertical Hall element contacts that are driven and vertical Hall element contacts from which output signals are received can be changed in a chopping sequence in a plurality of so-called “phases.”
- Typical chopping arrangements use two such phases, referred to herein as 2 ⁇ , or four such phases, referred to herein as 4 ⁇ , however, other chopping arrangements are also possible.
- the magnetic field sensor 100 can also include an electronic circuit 108 disposed on the planar surface 101 a and coupled to each one of the plurality of vertical Hall elements 103 .
- the electronic circuit 108 is configured to generate an output signal 108 a indicative of the angle of the projected component of the magnetic field.
- the electronic circuit 108 can be the same as or similar to that shown above in conjunction with FIG. 3 , wherein the CVH sensing element 72 is replaced by the plurality of vertical Hall elements 103 .
- each one of the plurality of vertical Hall elements 103 can be processed by the electronic circuit 108 sequentially.
- the plurality of vertical Hall elements 103 does not share vertical Hall element contacts. It will become apparent from discussion below in conjunction with FIG. 9 that such an arrangement tends to generate an output signal that has fewer and larger steps than the output signal 52 of FIG. 2 .
- the filter 102 of FIG. 3 can be adjusted to smooth out the steps. Because there are fewer steps in the output signal (see, e.g., FIGS. 2 and 9 ), a magnetic field sensor, like the magnetic field sensor 70 of FIG.
- the filter 102 introduces a fixed time delay, but does not necessarily impact the speed of operation, i.e., throughput of output samples.
- the plurality of vertical Hall elements 103 includes, and is arranged over, a common implant region in the planar surface 101 a of the substrate 101 .
- the electronic circuit 108 can include first and second vertical Hall element driving circuits 86 a , 86 b , respectively.
- the switching circuit 74 can be coupled between the first and second vertical Hall element driving circuits 86 a , 86 b and the plurality of vertical Hall elements 103 .
- the switching circuit 74 can be configured to switch couplings between the first and second vertical Hall element driving circuits 86 a , 86 b and the plurality of vertical Hall elements 103 , e.g., a changing two of the plurality of vertical Hall elements 103 . . . .
- each one of the plurality of vertical Hall elements 102 a , 102 b , 102 c , 102 d , 102 e , 102 f is responsive to (i.e., differently responsive to) the magnetic field 109 (or the projection 109 of a magnetic field) in the plane of the surface 101 a of the substrate 101 .
- each vertical Hall element generates (sequentially) an output signal related to an angle of the magnetic field 109 relative to an orientation of the respective vertical Hall element.
- the vertical Hall elements 102 b , 102 e for which lines between associated vertical Hall element contacts are perpendicular to the magnetic field 109 , have the greatest sensitivity.
- One of the vertical Hall elements 102 b , 102 e generates a largest positive output signal and the other one of the vertical Hall elements 102 b , 102 e generates a largest negative output signal. Other ones of the vertical Hall elements generate smaller output signals.
- the vertical Hall elements 102 b , 102 e generate output signals with approximately the same amplitude but with opposite signs.
- the amplitudes of the output signals from the two vertical Hall elements 102 b , 102 e i.e., a pair of vertical Hall elements, differ by small amounts due to small differences in sensitivity of the two vertical Hall elements 102 b , 102 e , due to small differences in offset voltage of the two vertical Hall elements 102 b , 102 e , and also due to position placement inaccuracy of the plurality of magnetic field sensing elements 103 relative to a magnet (not shown).
- the sensitivity difference can be reduced by integrated circuit fabrication techniques, including dimensional and process control.
- the offset voltage differences can be reduced by various techniques, for example, the above-described chopping.
- pairs of vertical Hall elements generate output signals with substantially the same amplitudes, but with opposite signs.
- it is possible to remove some of the vertical Hall elements for example, one, two, or three of the vertical Hall elements 102 a , 102 b , 102 d , 102 d , 102 e , 102 f and to still reconstruct the output signal using only the remaining vertical Hall elements.
- the magnetic field sensor 100 can generate an output signal more rapidly indicative of an angle of a magnetic field that the CVH sensing element of FIGS. 1 and 3 .
- the CVH sensing element described above in conjunction with FIG. 1 and the magnetic field sensor described above in conjunction with FIG. 3 when used with a 4 ⁇ (four phase) chopping, with a CVH sensing element with 64 CVH sensing elements, and with a master clock frequency of 8 MHz (see, e.g., clock 80 a of FIG. 3 ), results in a CVH sensing element sequence frequency (frequency of sample revolutions around CVH sensing element) of 31.25 kHz. This frequency is equivalent to a response time of the CVH sensing element (like cycle time of FIG. 2 , but for 64 CVH sensing elements) of about thirty-two microseconds.
- the magnetic field sensor 100 of FIG. 4 when used with 4 ⁇ chopping, with six vertical Hall elements as shown, and with a master clock of 8 MHz, results in a sequence frequency of 333 kHz and a response time of about three microseconds, much faster than the CVH sensing element. Furthermore, techniques described below in conjunction with FIGS. 7 , 7 A, 8 , and 8 A can reduce the number of vertical Hall elements further, for example, to three vertical Hall elements, resulting in a response time of about 1.5 microseconds. As described below, while hexagonal patterns of vertical Hall elements are used in examples herein, other patterns are also possible.
- a magnetic field sensor 110 is like the magnetic field sensor 100 of FIG. 4 .
- the magnetic field sensor 110 includes a plurality of vertical Hall elements 113 , individually 112 a , 112 b , 112 c , 112 d , 112 e , 112 f , arranged over separate implant regions 114 a , 114 b , 114 c , 114 d , 114 d , 114 f , respectively, in a substrate 111 .
- the magnetic field sensor 110 can be arranged on the semiconductor substrate 111 having a planar surface 111 a.
- An electronic circuit 118 is coupled to receive signals 113 a from the plurality of vertical Hall elements 113 .
- the electronic circuit 118 is configured to generate an output signal 118 a .
- the electronic circuit 118 and the output signal 118 a can be the same as or similar to the electronic circuit 108 and the output signal 108 a of FIG. 4 .
- a magnetic field sensor 120 includes a semiconductor substrate 121 having a planar surface 121 a .
- the magnetic field sensor 120 also includes a plurality of vertical Hall elements 123 .
- the plurality of vertical Hall elements 123 includes, as a primary plurality of vertical Hall elements, the vertical Hall elements 112 a , 112 b , 112 c , 112 d , 112 e , 112 f of FIG. 5 .
- the plurality of vertical Hall elements 123 also includes, as a secondary plurality of vertical Hall elements, vertical Hall elements 122 a , 122 b , 122 c , 122 d , 122 e , 122 f .
- the secondary plurality of vertical Hall elements is arranged over separate implant regions 124 a , 124 b , 124 c , 124 d , 124 e , 124 f respectively.
- FIG. 1 the arrangement of FIG.
- the primary plurality of vertical Hall elements 112 a , 112 b , 112 c , 112 d , 112 e , 112 f can be arranged over a first common implant region and the secondary plurality of vertical Hall elements 122 a , 122 b , 122 c , 122 d , 122 e , 122 f can be arranged over a second common implant region in the substrate 121 .
- each one of the secondary plurality of vertical Hall elements includes a respective plurality of vertical Hall element contacts like vertical Hall element contacts 116 a , 116 b , 116 c , 116 d , 116 e .
- Each plurality of secondary vertical Hall element contacts is arranged in a respective line.
- the lines of secondary vertical Hall element contacts are arranged in a pattern representative of a polygonal shape, here a hexagon.
- Each one of the lines of the secondary vertical Hall element contacts can be geometrically parallel to a respective line of the primary vertical Hall element contacts.
- the polygon of secondary vertical Hall elements can be rotated in relation to the polygon of primary vertical Hall elements. The rotation can be small, for example, 0.1 degrees, or the rotation can be large, for example thirty degrees.
- Each one of the primary plurality of vertical Hall elements 112 a , 112 b , 112 c , 112 d , 112 e , 112 f and each one of the secondary plurality of vertical Hall elements 122 a , 122 b , 122 c , 122 d , 122 e , 122 f is configured to generate a respective magnetic field signal responsive to of an angle of a projected component of a magnetic field (see, e.g., 110 of FIG. 4 ) projected upon the plane of the planar surface 121 a relative to an angular position of the respective vertical Hall element.
- sequential output signals from plurality of vertical Hall elements 123 are indicated as a signal 123 a .
- the signal 123 a can be similar to the differential signal 72 a , 72 b of FIG. 3 and similar to the signal 103 a of FIG. 4 and the signal 113 a of FIG. 5 .
- the magnetic field sensor 120 can also include an electronic circuit 126 disposed on the planar surface 121 a and coupled to each one of the plurality of vertical Hall elements 123 .
- the electronic circuit 126 is configured to generate an output signal 126 a indicative of the angle of the projected component of the magnetic field.
- the electronic circuit can be the same as or similar to that shown above in conjunction with FIG. 3 , wherein the CVH sensing element 72 is replaced by the plurality of vertical Hall elements 123 .
- each one of the plurality of vertical Hall elements 123 can be processed by the electronic circuit 126 sequentially, resulting in a pattern of twelve sequential samples within the signal 123 a .
- the vertical Hall elements 123 do not share vertical Hall element contacts. It will become apparent from discussion below in conjunction with FIG. 9 that such an arrangement tends to generate an output signal that has fewer and larger steps than the output signal 52 of FIG. 2 .
- the filter 102 of FIG. 3 can be adjusted to smooth out the steps.
- each one of the primary plurality of vertical Hall elements 112 a , 112 b , 112 c , 112 d , 112 e , 112 f is electronically coupled in parallel with an adjacent one of the secondary plurality of vertical Hall elements 122 a , 122 b , 122 c , 122 d , 122 e , 122 f , resulting in a pattern of six sequential samples within the signal 123 a.
- the electronically parallel arrangement can be accomplished in two different ways.
- a first parallel coupling only output signals of each adjacent pair of the plurality of vertical Hall elements 123 are coupled in parallel.
- drive signals provided to each one of the plurality of vertical Hall elements 123 in an adjacent pair of vertical Hall elements can be different.
- the different drive signals can be at different chopping phases at any time.
- output signals of each adjacent pair of the plurality of vertical Hall elements 123 are coupled in parallel, and also the drive signals to each adjacent pair of the plurality of vertical Hall elements 123 are coupled in parallel.
- output signals from each adjacent pair of the plurality of vertical Hall elements 123 are summed at a subsequent amplifier, with or without parallel drive signals to the vertical Hall elements 123 .
- the magnetic field sensor 120 can achieve higher signal-to-noise ratios than the magnetic field sensors 100 , 110 of FIG. 4 or 5 .
- the plurality of vertical Hall elements 123 is shown to include parallel pairs of vertical Hall elements, in other embodiments, there can be parallel groups of vertical Hall elements, each parallel group having two or more geometrically parallel vertical Hall elements.
- a magnetic field sensor 130 includes a semiconductor substrate 131 having a planar surface 131 a .
- the magnetic field sensor 130 also includes a plurality of vertical Hall elements 133 .
- the plurality of vertical Hall elements 133 includes, as a primary plurality of vertical Hall elements, primary vertical Hall elements 132 a , 132 b , 132 c .
- the plurality of vertical Hall elements 133 also includes, as a secondary plurality of vertical Hall elements, secondary vertical Hall elements 136 a , 136 b , 136 c .
- the primary and secondary pluralities of vertical Hall elements are arranged over separate implant regions 134 a , 134 b , 134 c , 138 a , 138 b , 138 c.
- Each one of the primary vertical Hall elements and each one of the secondary vertical Hall elements includes a respective plurality of vertical Hall element contacts.
- Each plurality of primary vertical Hall elements contacts and each plurality of secondary vertical Hall element contacts is arranged in a respective line.
- the lines of primary and secondary vertical Hall element contacts are arranged in a pattern representative of a portion of polygonal shape, here a portion of a hexagon.
- Each one of the lines of the secondary vertical Hall element contacts can be geometrically parallel to a respective line of the primary vertical Hall element contacts.
- each line of secondary vertical Hall elements can be rotated in relation to a respective line of primary vertical Hall elements. The rotation can be small, for example, 0.1 degrees, or the rotation can be large, for example thirty degrees.
- Each one of the primary plurality of vertical Hall elements 132 a , 132 b , 132 c and each one of the secondary plurality of vertical Hall elements 136 a , 136 b , 136 c is configured to generate a respective magnetic field signal responsive to of an angle of a projected component of the magnetic field projected upon the plane of the planar surface relative to an angular position of the respective vertical Hall element.
- sequential output signals from plurality of vertical Hall elements 133 are indicated as a signal 133 a .
- the signal 133 a can be similar to the differential signal 72 a , 72 b of FIG. 3 and similar to the signal 103 a of FIG. 4 , the signal 113 a of FIG. 5 , and the signal 123 a of FIG. 6 .
- the magnetic field sensor 130 can also include an electronic circuit 140 disposed on the planar surface 131 a and coupled to each one of the plurality of vertical Hall elements 133 .
- the electronic circuit 136 is configured to generate an output signal 140 a .
- the magnetic field sensor 130 can also include a pattern completion generator 142 coupled to receive the output signal 140 a and configured to generate an output signal 142 a indicative of the angle of the projected component of the magnetic field.
- the electronic circuit 140 can be the same as or similar to that shown above in conjunction with FIG. 3 , wherein the CVH sensing element 72 is replaced by the plurality of vertical Hall elements 133 .
- the electronic circuit 140 and the pattern completion generator 142 are both electronic circuits disposed upon the substrate 131 , and both together are referred to herein as an electronic circuit.
- each one of the plurality of vertical Hall elements 133 can be processed by the electronic circuit 140 sequentially, resulting in a pattern of six sequential samples within the signal 133 a .
- the plurality of vertical Hall elements 133 do not share vertical Hall element contacts. It will become apparent from discussion below in conjunction with FIG. 9 that such an arrangement tends to generate an output signal that has fewer and larger steps than the output signal 52 of FIG. 2 .
- the filter 102 of FIG. 3 can be adjusted to smooth out the steps.
- each one of the primary plurality of vertical Hall elements 132 a , 132 b , 132 c is electronically coupled in parallel with an adjacent one of the secondary plurality of vertical Hall elements 136 a , 136 b , 136 c , resulting in a pattern of three sequential samples within the signal 133 a.
- the electronically parallel arrangement can be accomplished in different ways.
- a first parallel coupling only output signals of each adjacent pair of the vertical Hall elements are coupled in parallel.
- drive signals provided to each one of the vertical Hall elements in an adjacent pair of vertical Hall elements can be different.
- the different drive signals can be at different chopping phases at any time.
- output signals of each adjacent pair of the vertical Hall elements are coupled in parallel, and also the drive signals to each adjacent pair of the vertical Hall elements are coupled in parallel.
- signals from lines of the primary and secondary vertical Hall elements can be combined at a subsequent amplifier.
- the magnetic field sensor 130 can achieve higher signal-to-noise ratios than the magnetic field sensors 100 , 110 of FIG. 4 or 5 .
- the plurality of vertical Hall elements 133 is representative of only a portion of a polygonal shape. However, as described above in conjunction with FIG. 4 , the plurality of vertical Hall elements 133 can be used to deduce other output signals as may be generated by vertical Hall elements that would otherwise form missing sides of the polygonal shape. Referring briefly to FIG. 6 , it will be understood that vertical Hall elements on opposite sides of the hexagonal shape have opposite output signals (i.e., signal values) but of the same amplitude when the magnetic field sensor 120 of FIG. 6 experiences a magnetic field in the plane of the surface 121 a . Thus, if a pair of vertical Hall elements 132 b , 136 b of FIG.
- the pattern completion generator 142 completes the hexagonal pattern by deducing or calculating electronic signals from those within the output signal 140 a , which calculated electronic signals are not directly generated by the plurality of vertical Hall elements 133 .
- the plurality of vertical Hall elements 133 is shown to include parallel pairs of vertical Hall elements, in other embodiments, there can be parallel groups of vertical Hall elements, each parallel group having two or more geometrically parallel vertical Hall elements.
- the magnetic field sensor 130 Comparing the magnetic field sensor 130 to the magnetic field sensor 120 of FIG. 6 , because the magnetic field sensor 130 only generates the output signals 133 a from three parallel pairs of vertical Hall elements and calculates other signals to represent a complete polygonal shape of vertical Hall elements, the magnetic field sensor 130 can achieve an indication of the angle of the magnetic field faster than the magnetic field sensor 120 of FIG. 6 .
- a magnetic field sensor 150 is similar to the magnetic field sensor 130 of FIG. 7 .
- the magnetic field sensor 150 includes a plurality of vertical Hall elements 153 that are representative of a different portion of a polygonal shape than the plurality of vertical Hall elements 133 of FIG. 7 . Nevertheless, elements of and function of the magnetic field sensor 150 will be understood from the discussion above in conjunction with FIG. 7 .
- a magnetic field sensor 170 is also similar to the magnetic field sensor 130 of FIG. 7 .
- the magnetic field sensor 170 includes a plurality of vertical Hall elements 173 having only three vertical Hall elements 172 a , 172 b , 172 c .
- the plurality of vertical Hall elements 173 does not include a secondary plurality of vertical Hall elements.
- An electronic circuit 176 and a pattern generator 178 can be the same as or similar to those described above in conjunction with FIG. 7 . Elements of and function of the magnetic field sensor 170 will be understood from the discussion above in conjunction with FIG. 7 .
- a magnetic field sensor 190 is also similar to the magnetic field sensor 150 of FIG. 7A .
- the magnetic field sensor 170 includes a plurality of vertical Hall elements 193 having only three vertical Hall elements 192 a , 192 b , 192 c .
- the plurality of vertical Hall elements 193 does not include a secondary plurality of vertical Hall elements.
- An electronic circuit 196 and a pattern generator 198 can be the same as or similar to those described above in conjunction with FIG. 7 . Elements of and function of the magnetic field sensor 190 will be understood from the discussion above in conjunction with FIGS. 7 and 7A .
- examples above show three (or six) vertical Hall elements with lines of vertical Hall element contacts arranged in half of hexagonal polygonal shapes, in other embodiments, other numbers of vertical Hall elements can be arranged with vertical Hall element contacts arranged in lines representative of other portions of polygonal shapes, for example, three quarters of a polygonal shape.
- each vertical Hall element can have more than five or fewer than five vertical Hall element contacts.
- FIG. 9 is a graph 210 is similar to the graph 50 of FIG. 2 .
- the graph 50 has a horizontal axis with a scale in units of vertical Hall element position, n, around a polygonal arrangement of vertical Hall elements, for example, around the plurality of vertical Hall elements 103 of FIG. 4 .
- the graph 210 also has a vertical axis with a scale in amplitude in units of millivolts.
- the graph 210 includes a signal 212 representative of output signal levels from the plurality of vertical Hall elements of 102 a , 102 b , 102 c , 102 d , 102 e , 102 f of FIG. 4 taken sequentially when in the presence of a magnetic field, stationary and pointing in a direction of sixty degrees.
- a maximum positive signal is achieved from one of the six vertical Hall elements 102 a , 102 b , 102 c , 102 d , 102 e , 102 f , which is best aligned with the magnetic field at sixty degrees, such that the line of vertical Hall element contacts (e.g., five contacts) of the vertical Hall element is closest to perpendicular to the magnetic field.
- a maximum negative signal is achieved from another vertical Hall, which is also aligned with the magnetic field 16 of FIG. 1 , such that the line of vertical Hall element contacts (e.g., five contacts) of the vertical Hall element is also perpendicular to the magnetic field.
- a sine wave 214 is provided to more clearly show the ideal behavior of the signal 212 .
- the sine wave can be generated by the filter 102 of FIG. 3 .
- the signal 214 can have variations due to vertical Hall element offsets, which tend to somewhat randomly cause element output signals to be too high or too low relative to the sine wave 214 , in accordance with offset errors for each element.
- the offset signal errors are undesirable.
- the offset errors can be reduced by the use of chopping described above. Chopping, as described above in conjunction with FIG. 4 , will be understood to be a process by which vertical Hall element contacts of each vertical Hall element are driven in different configurations and signals are received from different ones of the vertical Hall element contacts of each vertical Hall element to generate a plurality of output signals from each vertical Hall element.
- the plurality of signals can be arithmetically processed (e.g., summed or otherwise averaged) resulting in a signal with less offset.
- An offset generated by the vertical Hall elements induces non linearity in the sinusoidal signal (see, e.g., FIGS. 2 and 9 ) that can be further reduced with a filter (not shown) centered at or near the sinusoidal frequency.
- Groups of contacts of each vertical Hall element can be used in a chopped arrangement to generate chopped output signals from each vertical Hall element. Thereafter, a new group of adjacent vertical Hall element contacts can be selected (i.e., a new vertical Hall element). The new group can be used in the chopped arrangement to generate another chopped output signal from the next group, and so on.
- Each step of the signal 212 can be representative of a chopped output signal from one respective group of vertical Hall element contacts, i.e., from one respective vertical Hall element. However, in other embodiments, no chopping is performed and each step of the signal 212 is representative of an unchopped output signal from one respective group of vertical Hall element contacts, i.e., from one respective vertical Hall element.
- the graph 212 is representative of a CVH output signal with or without the above-described grouping and chopping of vertical Hall elements.
- a phase of the signal 212 e.g., a phase of the signal 214
- one or more of the vertical Hall elements can instead be a respective one or more magnetoresistance elements having respective axes of sensitivity aligned in the same directions as those of the above-described vertical Hall elements.
- other types of magnetic field sensing elements are possible, so long as they have axis of sensitivity aligned in the same directions as those of the above-described vertical Hall elements. It will be apparent how to modify the electronic circuit of FIG. 3 to use the various other types of magnetic field sensing elements.
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Abstract
Description
- Not Applicable.
- Not Applicable.
- This invention relates generally to magnetic field sensors and related fabrication techniques, and, more particularly, to a magnetic field sensor and corresponding fabrication technique having a plurality of vertical Hall elements arranged in at least a portion of a polygonal pattern and also having an electronic circuit coupled to the plurality of vertical Hall elements.
- Planar Hall elements and vertical Hall elements are known types of magnetic field sensing elements that can be used in magnetic field sensors. A planar Hall element tends to be responsive to magnetic field perpendicular to a surface of a substrate on which the planar Hall element is formed. A vertical Hall element tends to be responsive to magnetic field parallel to a surface of a substrate on which the vertical Hall element is formed.
- Other types of magnetic field sensing elements are known. For example, a so-called “circular vertical Hall” (CVH) sensing element, which includes a plurality of vertical magnetic field sensing elements, is known and described in PCT Patent Application No. PCT/EP2008/056517, entitled “Magnetic Field Sensor for Measuring Direction of a Magnetic Field in a Plane,” filed May 28, 2008, and published in the English language as PCT Publication No. WO 2008/145662, which application and publication thereof are incorporated by reference herein in their entirety. The CVH sensing element is a circular arrangement of vertical Hall elements arranged over a common circular implant region in a substrate. The CVH sensing element can be used to sense a direction (and optionally a strength) of a magnetic field in a plane of the substrate.
- Conventionally, all of the output signals from the plurality of vertical Hall elements within the CVH sensing element are needed in order to determine a direction of a magnetic field. Also conventionally, output signals from the vertical Hall elements of a CVH sensing element are generated sequentially, resulting in a substantial amount of time necessary to generate all of the output signals from the CVH sensing element. Thus, determination of the direction of the magnetic field can take a substantial amount of time.
- Various parameters characterize the performance of magnetic field sensing elements. These parameters include sensitivity, which is a change in an output signal of a magnetic field sensing element in response to a change of magnetic field experienced by the magnetic sensing element, and linearity, which is a degree to which the output signal of the magnetic field sensing element varies in direct proportion to the magnetic field. These parameters also include an offset, which is characterized by an output signal from the magnetic field sensing element not representative of a zero magnetic field when the magnetic field sensing element experiences a zero magnetic field.
- Another parameter that can characterize the performance of a CVH sensing element is the speed with which output signals from vertical Hall elements within the CVH sensing element can be sampled, and thus, the speed with which a direction of a magnetic field can be identified. Yet another parameter that can characterize the performance of a CVH sensing element is the resolution (e.g., angular step size) of the direction of the magnetic field that can be reported by the CVH sensing element.
- As described above, the CVH sensing element is operable, with associated circuits, to provide an output signal representative of an angle of a direction of a magnetic field. Therefore, as described below, if a magnet is disposed upon or otherwise coupled to a so-called “target object,” for example, a camshaft in an engine, the CVH sensing element can be used to provide an output signal representative of an angle of rotation, and/or a rotation speed, of the target object.
- For reasons described above, a magnetic field sensor that uses a CVH sensing element may have a limit as to how rapidly the magnetic field sensor can identify the direction of a magnetic field, i.e., a rotation angle or rotation speed of a target object. Furthermore, the magnetic field sensor may provide an angular resolution that is too low (too large an angle step size). In general, it may be possible to provide a higher resolution, but at the expense of more time.
- Thus, it would be desirable to provide a magnetic field sensing element (or, more generally, a plurality of magnetic field sensing elements) that can be used to generate an output signal more rapidly indicative of an angle of a magnetic field than a CVH sensing element.
- The present invention provides a magnetic field sensing element (or, more generally, a plurality of magnetic field sensing elements) that can be used to generate an output signal more rapidly indicative of an angle of a magnetic field than a CVH sensing element.
- In accordance with one aspect of the present invention, a magnetic field sensor includes a semiconductor substrate having a planar surface. The magnetic field sensor also includes a plurality of primary vertical Hall elements disposed on the planar surface. Each one of the plurality of primary vertical Hall elements includes a respective plurality of primary vertical Hall element contacts arranged in a respective line. The lines of primary vertical Hall element contacts are arranged in a pattern representative of at least a portion of a polygonal shape. The plurality of primary vertical Hall elements includes a primary vertical Hall element having a respective line of vertical Hall element contacts not parallel to a line of vertical Hall element contacts of another one of the plurality of primary vertical Hall elements. Each one of the plurality of primary vertical Hall elements is configured to generate a respective magnetic field signal indicative of a projected component of a magnetic field projected upon the plane of the planar surface relative to an angular position of the respective vertical Hall element. The magnetic field sensor also includes an electronic circuit disposed on the planar surface and coupled to each one of the plurality of primary vertical Hall elements. The electronic circuit is configured to generate an output signal indicative of an angle of the projected component of the magnetic field.
- In some embodiments, the magnetic field sensor also includes a plurality of secondary vertical Hall elements disposed on the planar surface. Each one of the secondary vertical Hall elements includes a respective plurality of secondary vertical Hall element contacts arranged in a respective line. Each one of the plurality of secondary vertical Hall elements is arranged in a respective group with a respective one of the plurality of primary vertical Hall elements. Each line of secondary vertical Hall element contacts is geometrically arranged at a predetermined angle with a respective line of primary vertical Hall element contacts to form a plurality of parallel groups of vertical Hall elements.
- In accordance with another aspect of the present invention, a method of fabricating a magnetic field sensor includes providing a semiconductor substrate having a planar surface. The method also includes forming, on the planar surface, a plurality of primary vertical Hall elements. Each one of the plurality of primary vertical Hall elements comprises a respective plurality of vertical Hall element contacts arranged in a respective line of primary vertical Hall element contacts. The lines of primary vertical Hall element contacts are arranged in a pattern representative of at least a portion a polygonal shape. The plurality of primary vertical Hall elements includes a primary vertical Hall element having a respective line of vertical Hall element contacts not parallel to a line of vertical Hall element contacts of another one of the plurality of primary vertical Hall elements. Each one of the plurality of primary vertical Hall elements is configured to generate a respective magnetic field signal indicative of a projected component of a magnetic field projected upon the plane of the planar surface relative to an angular position of the respective vertical Hall element. The method also includes forming, on the semiconductor substrate, an electronic circuit coupled to each one of the plurality of primary vertical Hall elements. The electronic circuit is configured to generate an output signal representative of an angle of the projected component of the magnetic field.
- In some embodiments, the method also includes forming, on the planar surface, a plurality of secondary vertical Hall elements. Each one of the secondary vertical Hall elements includes a respective plurality of secondary vertical Hall element contacts arranged in a respective line. Each one of the plurality of secondary vertical Hall elements is arranged in a respective group with a respective one of the plurality of primary vertical Hall elements. Each line of secondary vertical Hall element contacts is geometrically arranged at a predetermined angle with a respective line of primary vertical Hall element contacts to form a plurality of parallel groups of vertical Hall elements.
- In accordance with another aspect of the present invention, a magnetic field sensor includes a semiconductor substrate having a planar surface. The magnetic field sensor also includes a plurality of magnetic field sensing elements disposed on the planar surface. The plurality of magnetic field sensing elements has a respective plurality of major response axes, each major response axis parallel to the major surface. The plurality of major response axes is arranged in a pattern representative of at least a portion of a polygonal shape. The plurality of magnetic field sensing elements includes a primary vertical Hall element having a major response axis not parallel to major response axis of another one of the plurality of magnetic field sensing elements. Each one of the plurality of magnetic field sensing elements is configured to generate a respective magnetic field signal indicative of a projected component of a magnetic field projected upon the plane of the planar surface relative to an angular position of the response axis of the respective magnetic field sensing element. The magnetic field sensor also includes an electronic circuit disposed on the planar surface and coupled to each one of the plurality of magnetic field sensing elements. The electronic circuit is configured to generate an output signal indicative of an angle of the projected component of the magnetic field.
- In some embodiments of the magnetic field sensor, the plurality of magnetic field sensing elements comprises a plurality of magnetoresistance elements.
- In accordance with another aspect of the present invention, a method of fabricating a magnetic field sensor includes providing a semiconductor substrate having a planar surface. The method also includes forming, on the planar surface, a plurality of magnetic field sensing elements having a respective plurality of major response axes, each major response axis parallel to the major surface. The plurality of major response axes is arranged in a pattern representative of at least a portion of a polygonal shape. The plurality of magnetic field sensing elements includes a primary vertical Hall element having a major response axis not parallel to major response axis of another one of the plurality of magnetic field sensing elements. Each one of the plurality of magnetic field sensing elements is configured to generate a respective magnetic field signal indicative of a projected component of a magnetic field projected upon the plane of the planar surface relative to an angular position of the response axis of the respective magnetic field sensing element. The method also includes forming, on the semiconductor substrate, an electronic circuit coupled to each one of the plurality of magnetic field sensing elements. The electronic circuit is configured to generate an output signal indicative of an angle of the projected component of the magnetic field.
- In some embodiments of the method, the plurality of magnetic field sensing elements comprises a plurality of magnetoresistance elements.
- The foregoing features of the invention, as well as the invention itself may be more fully understood from the following detailed description of the drawings, in which:
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FIG. 1 is a pictorial showing a circular vertical Hall (CVH) sensing element having a plurality of vertical Hall elements arranged in a circle over a common implant region in a substrate and a two pole ring magnet disposed close to the CVH sensing element; -
FIG. 2 is a graph showing an output signal as may be generated by the CVH sensing element ofFIG. 1 ; -
FIG. 3 is a block diagram showing an electronic circuit using a CVH sensing element to determine a direction of a sensed magnetic field; -
FIG. 4 is a pictorial of an exemplary magnetic field sensor having six vertical Hall elements arranged in a hexagonal pattern over a common implant region in a substrate; -
FIG. 5 is a pictorial of another exemplary magnetic field sensor having six vertical Hall elements arranged in a hexagonal pattern, each arranged over separate implant regions; -
FIG. 6 is a pictorial of another exemplary magnetic field sensor having six primary vertical Hall elements arranged in a hexagonal pattern and also having six secondary vertical Hall elements arranged in a hexagonal pattern; -
FIG. 7 is a pictorial of another exemplary magnetic field sensor having three primary vertical Hall elements arranged a portion of (here half of) a hexagonal pattern and also having three secondary vertical Hall elements arranged in a half of a hexagonal pattern; -
FIG. 7A is a pictorial of another exemplary magnetic field sensor having three primary vertical Hall elements arranged in a portion of (here half of) of a hexagonal pattern and also having three secondary vertical Hall elements arranged in a half of a hexagonal pattern; -
FIG. 8 is a pictorial of another exemplary magnetic field sensor having three vertical Hall elements arranged a portion of (here half of) of a hexagonal pattern; -
FIG. 8A is a pictorial of another exemplary magnetic field sensor having three vertical Hall elements arranged a portion of (here half of) of a hexagonal pattern; and -
FIG. 9 is a graph showing output signal that can be generated by the vertical Hall elements of the arrangement ofFIGS. 4 and 5 . - Before describing the present invention, some introductory concepts and terminology are explained. As used herein, the term “magnetic field sensing element” is used to describe a variety of electronic elements that can sense a magnetic field. The magnetic field sensing elements can be, but are not limited to, Hall Effect elements, magnetoresistance elements, or magnetotransistors. As is known, there are different types of Hall Effect elements, for example, a planar Hall element, a vertical Hall element, and a circular Hall element. As is also known, there are different types of magnetoresistance elements, for example, a giant magnetoresistance (GMR) element, an anisotropic magnetoresistance element (AMR), a tunneling magnetoresistance (TMR) element, an Indium antimonide (InSb) sensor, and a magnetic tunnel junction (MTJ).
- As used herein, the term “sensor” is used to describe a circuit or assembly that includes a sensing element and other components. In particular, as used herein, the term “magnetic field sensor” is used to describe a circuit or assembly that includes a magnetic field sensing element and electronics coupled to the magnetic field sensing element.
- A used herein the terms “primary” and “secondary” are used to denote different physical entities and not to denote any structural or functional differences.
- As is known, some of the above-described magnetic field sensing elements tend to have an axis of maximum sensitivity parallel to a substrate that supports the magnetic field sensing element, and others of the above-described magnetic field sensing elements tend to have an axis of maximum sensitivity perpendicular to a substrate that supports the magnetic field sensing element. In particular, planar Hall elements tend to have axes of sensitivity perpendicular to a substrate, while magnetoresistance elements and vertical Hall elements (including circular vertical Hall (CVH) sensing elements) tend to have axes of sensitivity parallel to a substrate.
- Magnetic field sensors are used in a variety of applications, including, but not limited to, an angle sensor that senses an angle of a direction of a magnetic field, a current sensor that senses a magnetic field generated by a current carried by a current-carrying conductor, a magnetic switch that senses the proximity of a ferromagnetic object, a rotation detector that senses passing ferromagnetic articles, for example, magnetic domains of a ring magnet, and a magnetic field sensor that senses a magnetic field density of a magnetic field.
- While embodiments shown and described below indicate vertical Hall elements with vertical Hall element contacts arranged in straight lines, in other embodiments, the vertical Hall element contacts of one or more of the vertical Hall elements can be arranged in respective arcs. Thus, as used herein, the term “line” is used to describe either a straight line or a curved line.
- Referring to
FIG. 1 , a circular vertical Hall (CVH) sensingelement 12 includes acircular implant region 18 having a plurality of vertical Hall elements disposed thereon, of which avertical Hall element 12 a is but one example. Each vertical Hall element has a plurality of Hall element contacts (e.g., four or five contacts), of which a verticalHall element contact 12 aa is but one example. - A particular vertical Hall element (e.g., 12 a) within the
CVH sensing element 12, which, for example, can have five adjacent contacts, can share some, for example, four, of the five contacts with a next vertical Hall element (e.g., 12 b). Thus, a next vertical Hall element can be shifted by one contact from a prior vertical Hall element. For such shifts by one contact, it will be understood that the number of vertical Hall elements is equal to the number of vertical Hall element contacts, e.g., 32. However, it will also be understood that a next vertical Hall element can be shifted by more than one contact from the prior vertical Hall element, in which case, there are fewer vertical Hall elements than there are vertical Hall element contacts in the CVH sensing element. - A center of a vertical Hall element 0 is positioned along an
x-axis 20 and a center ofvertical Hall element 8 is positioned along a y-axis 22. In theexemplary CVH 12, there are thirty-two vertical Hall elements and thirty-two vertical Hall element contacts. However, a CVH can have more than or fewer than thirty-two vertical Hall elements and more than or fewer than thirty-two vertical Hall element contacts. - In some applications, a
circular magnet 14 having asouth side 14 a and anorth side 14 b can be disposed over theCVH 12. Thecircular magnet 14 tends to generate amagnetic field 16 having a direction from thenorth side 14 a to thesouth side 14 b, here shown to be pointed to a direction of about forty-five degrees relative tox-axis 20. Other magnets having other shapes and configurations are possible. - In some applications, the
circular magnet 14 is mechanically coupled to a rotating object (a target object), for example, an automobile crank shaft or an automobile camshaft, and is subject to rotation relative to theCVH sensing element 12. With this arrangement, theCVH sensing element 12 in combination with an electronic circuit described below can generate a signal related to the angle of rotation of themagnet 14. - The
CVH sensing element 12 can be disposed upon asubstrate 26, for example, a silicon substrate, along with other electronics (not shown). - Referring now to
FIG. 2 , agraph 50 has a horizontal axis with a scale in units of CVH vertical Hall element position, n, around a CVH sensing element, for example, theCVH sensing element 12 ofFIG. 1 . Thegraph 50 also has a vertical axis with a scale in amplitude in units of millivolts. - The
graph 50 includes asignal 52 representative of output signal levels from the plurality of vertical Hall elements of the CVH taken sequentially with the magnetic field ofFIG. 1 stationary and pointing in a direction of forty-five degrees. - Referring briefly to
FIG. 1 , as described above, vertical Hall element 0 is centered along thex-axis 20 andvertical Hall element 8 is centered along the y-axis 22. In the exemplaryCVH sensing element 12, there are thirty-two vertical Hall element contacts and a corresponding thirty-two vertical Hall elements, each vertical Hall element having a plurality of vertical Hall element contacts, for example, five contacts. - In
FIG. 2 , a maximum positive signal is achieved from a vertical Hall element centered atposition 4, which is aligned with themagnetic field 16 ofFIG. 1 , such that a line drawn between the vertical Hall element contacts (e.g., five contacts) of the vertical Hall element atposition 4 is perpendicular to the magnetic field. A maximum negative signal is achieved from a vertical Hall element centered atposition 20, which is also aligned with themagnetic field 16 ofFIG. 1 , such that a line drawn between the vertical Hall element contacts (e.g., five contacts) of the vertical Hall element atposition 20 is also perpendicular to the magnetic field. - A
sine wave 54 is provided to more clearly show the ideal behavior of thesignal 52. Thesignal 52 has variations due to vertical Hall element offsets, which tend to somewhat randomly cause element output signals to be too high or too low relative to thesine wave 54, in accordance with offset errors for each element. The offset signal errors are undesirable. In some embodiments, the offset errors can be reduced by “chopping” each vertical Hall element. Chopping will be understood to be a process by which vertical Hall element contacts of each vertical Hall element are driven in different configurations and signals are received from different ones of the vertical Hall element contacts of each vertical Hall element to generate a plurality of output signals from each vertical Hall element. The plurality of signals can be arithmetically processed (e.g., summed or otherwise averaged) resulting in a signal with less offset. - Full operation of the
CVH sensing element 12 ofFIG. 1 and generation of thesignal 52 ofFIG. 2 are described in more detail in the above-described PCT Patent Application No. PCT/EP2008/056517, entitled “Magnetic Field Sensor for Measuring Direction of a Magnetic Field in a Plane,” filed May 28, 2008, which is published in the English language as PCT Publication No. WO 2008/145662. - As will be understood from PCT Patent Application No. PCT/EP2008/056517, groups of contacts of each vertical Hall element can be used in a chopped arrangement to generate chopped output signals from each vertical Hall element. Thereafter, a new group of adjacent vertical Hall element contacts can be selected (i.e., a new vertical Hall element), which can be offset by one or more elements from the prior group. The new group can be used in the chopped arrangement to generate another chopped output signal from the next group, and so on.
- Each step of the
signal 52 can be representative of a chopped output signal from one respective group of vertical Hall element contacts, i.e., from one respective vertical Hall element. However, in other embodiments, no chopping is performed and each step of thesignal 52 is representative of an unchopped output signal from one respective group of vertical Hall element contacts, i.e., from one respective vertical Hall element. Thus, thegraph 52 is representative of a CVH output signal with or without the above-described grouping and chopping of vertical Hall elements. - It will be understood that, using techniques described above in PCT Patent Application No. PCT/EP2008/056517, a phase of the signal 52 (e.g., a phase of the signal 54) can be found and can be used to identify the pointing direction of the
magnetic field 16 ofFIG. 1 relative to theCVH sensing element 12. - Referring now to
FIG. 3 , amagnetic field sensor 70 includes asensing portion 71. The sensingportion 71 can include aCVH sensing element 72 having a plurality of CVH sensing element contacts, e.g., a CVHsensing element contact 73. In some embodiments there are thirty-two vertical Hall elements in theCVH sensing element 72 and a corresponding thirty-two CVH sensing element contacts. In other embodiments there are sixty-four vertical Hall elements in theCVH sensing element 72 and a corresponding sixty-four CVH sensing element contacts. However, in other embodiments, theCVH sensing element 72 can have more than or fewer than thirty-two vertical Hall elements and/or more than or fewer than thirty-two vertical Hall element contacts. - A magnet (not shown) can be disposed proximate to the
CVH sensing element 72, and can be coupled to a target object (not shown). The magnet can be the same as or similar to themagnet 14 ofFIG. 1 - As described above, the
CVH sensing element 72 can have a plurality of vertical Hall elements, each vertical Hall element comprising a group of vertical Hall element contacts (e.g., five vertical Hall element contacts), of which the verticalHall element contact 73 is but one example. - In some embodiments, a switching
circuit 74 can provide sequential CVH differential output signals 72 a, 72 b from theCVH sensing element 72. - The CVH
differential output signal 72 a, 72 b is comprised of sequential output signals taken one-at-a-time around theCVH sensing element 72, wherein each output signal is generated on a separate signal path and switched by the switchingcircuit 74 into the path of thedifferential output signal 72 a, 72 b. Thesignal 52 ofFIG. 2 can be representative of thedifferential signal 72 a, 72 b. Therefore, the CVHdifferential output signal 72 a, 72 b can be represented as a switched set of CVH output signals xn=x0 to xN-1, taken one at a time, where n is equal to a vertical Hall element position (i.e., a position of a group of vertical Hall element contacts that form a vertical Hall element) in theCVH sensing element 72, and where there are N such positions. - In one particular embodiment, the number of vertical Hall elements (each comprising a group of vertical Hall element contacts) in the
CVH sensing element 72 is equal to the total number of sensing element positions, N. In other words, the CVHdifferential output signal 72 a, 72 b can be comprised of sequential output signals, wherein the CVHdifferential output signal 72 a, 72 b is associated with respective ones of the vertical Hall elements in theCVH sensing element 72 as the switchingcircuit 74 steps around the vertical Hall elements of theCVH sensing element 72 by increments of one, and N equals the number of vertical Hall elements in theCVH sensing element 72. However, in other embodiments, the increments can be by greater than one vertical Hall element, in which case N is less than the number of vertical Hall elements in theCVH sensing element 72. - In one particular embodiment, the
CVH sensing element 72 has thirty-two vertical Hall elements, i.e., N=32, and each step is a step of one vertical Hall element contact position (i.e., one vertical Hall element position). However, in other embodiments, there can be more than thirty-two or fewer than thirty-two vertical Hall elements in theCVH sensing element 72, for example sixty-four vertical Hall elements. Also, the increments of vertical Hall element positions, n, can be greater than one vertical Hall element contact. - In some embodiments, another switching
circuit 76 can provide the above-described “chopping” of groups of the vertical Hall elements within theCVH sensing element 72. Chopping will be understood to be an arrangement in which a group of vertical Hall element contacts, for example, five vertical Hall element contacts that form one vertical Hall element, are driven withcurrent sources 86 in a plurality of different connection configurations, and signals are received from the group of vertical Hall element contacts in corresponding different configurations to generate the CVHdifferential output signal 72 a, 72 b. Thus, in accordance to with each vertical Hall element position, n, there can be a plurality of sequential output signals during the chopping, and then the group increments to a new group, for example, by an increment of one vertical Hall element contact. - The sensing
portion 71 can also includecurrent sources 86 configured to drive theCVH sensing element 72. Whilecurrent sources 86 are shown, in other embodiments, thecurrent sources 86 can be replaced by voltage sources. - The
magnetic field sensor 70 includes anoscillator 78 that provides clock signals 78 a, 78 b, 78 c, which can have the same or different frequencies. Adivider 80 is coupled to receive theclock signal 78 a and configured to generate a dividedclock signal 80 a. Aswitch control circuit 82 is coupled to receive the dividedclock signal 80 a and configured to generate switch control signals 82 a, which are received by the switchingcircuits CVH sensing element 72, and optionally, to control the chopping of groups of vertical Hall elements within theCVH sensing element 72 in ways described above. - The
magnetic field sensor 70 can include adivider 88 coupled to receive theclock signal 78 c and configured to generate a dividedclock signal 88 a, also referred to herein as an “angle update clock” signal. - The
magnetic field sensor 70 also includes an x-y direction component circuit 90. The x-y direction component circuit 90 can include anamplifier 92 coupled to receive the CVH differential output signals 72 a, 72 b. Theamplifier 92 is configured to generate an amplifiedsignal 92 a. Abandpass filter 94 is coupled to receive the amplifiedsignal 92 a and configured to generate a filtered signal 94 a. Acomparator 96, with or without hysteresis, is configured to receive the filtered signal 94 a. Thecomparator 96 is also coupled to receive athreshold signal 120. Thecomparator 96 is configured to generate athresholded signal 96 a generated by comparison of the filtered signal 94 a with thethreshold signal 120. - The x-y direction component circuit 90 also includes an
amplifier 114 coupled to receive the dividedclock signal 88 a. Theamplifier 114 is configured to generate an amplifiedsignal 114 a. Abandpass filter 116 is coupled to receive the amplifiedsignal 114 a and configured to generate afiltered signal 116 a. Acomparator 118, with or without hysteresis, is coupled to receive the filteredsignal 116 a. Thecomparator 118 is also coupled to receive athreshold signal 122. Thecomparator 118 is configured to generate athresholded signal 118 a by comparison of the filteredsignal 116 a with thethreshold signal 122. - The bandpass filters 94, 116 can have center frequencies equal to 1/T, where T is the time that it takes to sample all of the vertical Hall elements within the
CVH sensing element 72. - It should be understood that the
amplifier 114, thebandpass filter 116, and thecomparator 118 provide a delay of the dividedclock signal 88 a in order to match a delay of the circuit channel comprised of theamplifier 92, thebandpass filter 94, and thecomparator 96. The matched delays provide phase matching, in particular, during temperature excursions of themagnetic field sensor 70. - A
counter 98 can be coupled to receive thethresholded signal 96 a at an enable input, to receive theclock signal 78 b at a clock input, and to receive thethresholded signal 118 a at a reset input. - The
counter 98 is configured to generate aphase signal 98 a having a count representative of a phase difference between thethresholded signal 96 a and thethresholded signal 118 a. - The
phase shift signal 98 a is received by alatch 100 that is latched upon an edge of the dividedclock signal 88 a. Thelatch 100 is configured to generate a latchedsignal 100 a, also referred to herein as an “x-y angle signal.” - It will be apparent that the latched
signal 100 a is a multi-bit digital signal that has a value representative of a direction of an angle of the magnetic field experience by theCVH sensing element 72, and thus, an angle of the magnet and target object. Thesignal 52 ofFIG. 2 is representative of the latchedsignal 100 a. - In some embodiments, the
magnetic field sensor 70 can also include afilter 102 coupled to receive the latchedsignal 100 a and configured to generate afiltered signal 102 a. Thesignal 54 ofFIG. 2 is representative of the filteredsignal 102 a. - In some embodiments, the clock signals 78 a, 78 b, 78 c each have a frequency of about 30 MHz, the divided
clock signal 80 a has a frequency of about 8 MHz, and the angleupdate clock signal 88 a has a frequency of about 30 kHz. However in other embodiments, the initial frequencies can be higher or lower than these frequencies - With the
magnetic field sensor 70, it will be appreciated that an update rate of the x-y angle signal 100 a occurs at a rate equivalent to a rate at which all of the vertical Hall elements within theCVH sensing element 72 are collectively sampled. An exemplary rate is described below in conjunction withFIG. 4 - Referring again briefly to
FIG. 2 , it will be understood that all of the vertical Hall elements within theCVH sensing element 72 are sampled in sequence to achieve an update of the x-y angle signal 100 a. Sampling all of the vertical Hall elements can take an appreciable amount of time. - Referring now to
FIG. 4 , amagnetic field sensor 100 includes asemiconductor substrate 101 having a planar surface 101 a. Themagnetic field sensor 100 also includes a plurality ofvertical Hall elements 103, individually 102 a, 102 b, 102 c, 102 d, 102 e, 102 f, disposed on the planar surface 101 a. Taking thevertical Hall elements 102 a as being representative of other ones of the plurality of vertical Hall elements, each one of the vertical Hall elements includes a respective plurality of vertical Hall element contacts like verticalHall element contacts - Each one of the plurality of
vertical Hall elements component 109 of a magnetic field projected upon the plane of the planar surface 101 a relative to an angular position of the respective vertical Hall element. A magnet is not shown, but can be the same as or signal to themagnet 18 ofFIG. 1 and disposed proximate to the plurality of magneticfield sensing elements 103. Here, sequential output signals from the plurality ofvertical Hall elements 103 are indicated as asignal 103 a. Thesignal 103 a can be similar to thedifferential signal 72 a, 72 b ofFIG. 3 . - Again taking the
vertical Hall element 102 a is being representative of other ones of the vertical Hall elements, thevertical Hall element 102 a is operated by driving a current into selected ones, e.g., two, of the verticalHall element contacts vertical Hall element 102 a, the selection of vertical Hall element contacts that are driven and vertical Hall element contacts from which output signals are received can be changed in a chopping sequence in a plurality of so-called “phases.” Typical chopping arrangements use two such phases, referred to herein as 2×, or four such phases, referred to herein as 4×, however, other chopping arrangements are also possible. - The
magnetic field sensor 100 can also include anelectronic circuit 108 disposed on the planar surface 101 a and coupled to each one of the plurality ofvertical Hall elements 103. Theelectronic circuit 108 is configured to generate anoutput signal 108 a indicative of the angle of the projected component of the magnetic field. Theelectronic circuit 108 can be the same as or similar to that shown above in conjunction withFIG. 3 , wherein theCVH sensing element 72 is replaced by the plurality ofvertical Hall elements 103. - In operation, each one of the plurality of
vertical Hall elements 103 can be processed by theelectronic circuit 108 sequentially. Unlike themagnetic field sensor 70 ofFIG. 3 , for which vertical Hall elements within theCVH sensing element 72 overlap and share vertical Hall element contacts, here, the plurality ofvertical Hall elements 103 does not share vertical Hall element contacts. It will become apparent from discussion below in conjunction withFIG. 9 that such an arrangement tends to generate an output signal that has fewer and larger steps than theoutput signal 52 ofFIG. 2 . However, thefilter 102 ofFIG. 3 can be adjusted to smooth out the steps. Because there are fewer steps in the output signal (see, e.g.,FIGS. 2 and 9 ), a magnetic field sensor, like themagnetic field sensor 70 ofFIG. 3 , that uses the plurality ofvertical Hall elements 103, can run at high speeds (i.e., speeds of rotation of a sensed magnetic field). Thefilter 102 introduces a fixed time delay, but does not necessarily impact the speed of operation, i.e., throughput of output samples. - The plurality of
vertical Hall elements 103 includes, and is arranged over, a common implant region in the planar surface 101 a of thesubstrate 101. - Referring briefly again to
FIG. 3 , in some embodiments, theelectronic circuit 108 can include first and second vertical Hall element driving circuits 86 a, 86 b, respectively. The switchingcircuit 74 can be coupled between the first and second vertical Hall element driving circuits 86 a, 86 b and the plurality ofvertical Hall elements 103. Not to be confused with chopping, which dwells upon one vertical Hall element at a time, the switchingcircuit 74 can be configured to switch couplings between the first and second vertical Hall element driving circuits 86 a, 86 b and the plurality ofvertical Hall elements 103, e.g., a changing two of the plurality ofvertical Hall elements 103 . . . . During a time when one of the plurality ofvertical Hall elements 103 is being driven by the first vertical Hall element driving circuit 86 a and processed by theelectronic circuit 108, another one of the plurality ofvertical Hall elements 103 can be driven by the second vertical Hall element driving circuit 86 b. With this arrangement, theelectronic circuit 108 can more rapidly sequence through the plurality of vertical Hall elements, since a next vertical Hall element can be ready for sampling when sampling of a present vertical Hall element is complete. - As described above, each one of the plurality of
vertical Hall elements projection 109 of a magnetic field) in the plane of the surface 101 a of thesubstrate 101. In particular, each vertical Hall element generates (sequentially) an output signal related to an angle of themagnetic field 109 relative to an orientation of the respective vertical Hall element. For themagnetic field 109 shown at a particular angle, thevertical Hall elements 102 b, 102 e, for which lines between associated vertical Hall element contacts are perpendicular to themagnetic field 109, have the greatest sensitivity. One of thevertical Hall elements 102 b, 102 e generates a largest positive output signal and the other one of thevertical Hall elements 102 b, 102 e generates a largest negative output signal. Other ones of the vertical Hall elements generate smaller output signals. - For the
magnetic field 109 shown at the particular angle, it will also be appreciated that thevertical Hall elements 102 b, 102 e generate output signals with approximately the same amplitude but with opposite signs. The amplitudes of the output signals from the twovertical Hall elements 102 b, 102 e, i.e., a pair of vertical Hall elements, differ by small amounts due to small differences in sensitivity of the twovertical Hall elements 102 b, 102 e, due to small differences in offset voltage of the twovertical Hall elements 102 b, 102 e, and also due to position placement inaccuracy of the plurality of magneticfield sensing elements 103 relative to a magnet (not shown). The sensitivity difference can be reduced by integrated circuit fabrication techniques, including dimensional and process control. The offset voltage differences can be reduced by various techniques, for example, the above-described chopping. - For the
magnetic field 109 shown at the particular angle, other pairs of vertical Hall elements also generate output signals with the same amplitude but with different signs. The verticalHall element pair 102 c, 102 f and also the verticalHall element pair Hall element pair 102 b, 102 e. - For a magnetic field at other angles in the plane of the surface 101 a, similarly, pairs of vertical Hall elements generate output signals with substantially the same amplitudes, but with opposite signs. Thus, as described below in conjunction with
FIGS. 7 , 7A, 8, and 8A, it is possible to remove some of the vertical Hall elements, for example, one, two, or three of thevertical Hall elements - The
magnetic field sensor 100 can generate an output signal more rapidly indicative of an angle of a magnetic field that the CVH sensing element ofFIGS. 1 and 3 . The CVH sensing element described above in conjunction withFIG. 1 and the magnetic field sensor described above in conjunction withFIG. 3 , when used with a 4× (four phase) chopping, with a CVH sensing element with 64 CVH sensing elements, and with a master clock frequency of 8 MHz (see, e.g.,clock 80 a ofFIG. 3 ), results in a CVH sensing element sequence frequency (frequency of sample revolutions around CVH sensing element) of 31.25 kHz. This frequency is equivalent to a response time of the CVH sensing element (like cycle time ofFIG. 2 , but for 64 CVH sensing elements) of about thirty-two microseconds. - In comparison, the
magnetic field sensor 100 ofFIG. 4 , when used with 4× chopping, with six vertical Hall elements as shown, and with a master clock of 8 MHz, results in a sequence frequency of 333 kHz and a response time of about three microseconds, much faster than the CVH sensing element. Furthermore, techniques described below in conjunction withFIGS. 7 , 7A, 8, and 8A can reduce the number of vertical Hall elements further, for example, to three vertical Hall elements, resulting in a response time of about 1.5 microseconds. As described below, while hexagonal patterns of vertical Hall elements are used in examples herein, other patterns are also possible. - Referring now to
FIG. 5 , amagnetic field sensor 110 is like themagnetic field sensor 100 ofFIG. 4 . However themagnetic field sensor 110 includes a plurality ofvertical Hall elements 113, individually 112 a, 112 b, 112 c, 112 d, 112 e, 112 f, arranged overseparate implant regions substrate 111. - The
magnetic field sensor 110 can be arranged on thesemiconductor substrate 111 having aplanar surface 111 a. - An
electronic circuit 118 is coupled to receive signals 113 a from the plurality ofvertical Hall elements 113. Theelectronic circuit 118 is configured to generate anoutput signal 118 a. Theelectronic circuit 118 and theoutput signal 118 a can be the same as or similar to theelectronic circuit 108 and theoutput signal 108 a ofFIG. 4 . - Referring now to
FIG. 6 , amagnetic field sensor 120 includes asemiconductor substrate 121 having aplanar surface 121 a. Themagnetic field sensor 120 also includes a plurality ofvertical Hall elements 123. The plurality ofvertical Hall elements 123 includes, as a primary plurality of vertical Hall elements, thevertical Hall elements FIG. 5 . Unlike themagnetic field sensor 110 ofFIG. 5 , the plurality ofvertical Hall elements 123 also includes, as a secondary plurality of vertical Hall elements,vertical Hall elements separate implant regions FIG. 4 , in other embodiments, the primary plurality ofvertical Hall elements vertical Hall elements substrate 121. - Taking the secondary
vertical Hall element 122 a as being representative of other ones of the plurality of vertical Hall elements, each one of the secondary plurality of vertical Hall elements includes a respective plurality of vertical Hall element contacts like verticalHall element contacts - Each one of the primary plurality of
vertical Hall elements vertical Hall elements FIG. 4 ) projected upon the plane of theplanar surface 121 a relative to an angular position of the respective vertical Hall element. Here, sequential output signals from plurality ofvertical Hall elements 123 are indicated as a signal 123 a. The signal 123 a can be similar to thedifferential signal 72 a, 72 b ofFIG. 3 and similar to thesignal 103 a ofFIG. 4 and the signal 113 a ofFIG. 5 . - The
magnetic field sensor 120 can also include anelectronic circuit 126 disposed on theplanar surface 121 a and coupled to each one of the plurality ofvertical Hall elements 123. Theelectronic circuit 126 is configured to generate anoutput signal 126 a indicative of the angle of the projected component of the magnetic field. The electronic circuit can be the same as or similar to that shown above in conjunction withFIG. 3 , wherein theCVH sensing element 72 is replaced by the plurality ofvertical Hall elements 123. - In operation, in some embodiments, each one of the plurality of
vertical Hall elements 123 can be processed by theelectronic circuit 126 sequentially, resulting in a pattern of twelve sequential samples within the signal 123 a. Unlike themagnetic field sensor 70 ofFIG. 3 , for which vertical Hall elements within theCVH sensing element 72 overlap and share vertical Hall element contacts, here, thevertical Hall elements 123 do not share vertical Hall element contacts. It will become apparent from discussion below in conjunction withFIG. 9 that such an arrangement tends to generate an output signal that has fewer and larger steps than theoutput signal 52 ofFIG. 2 . However, thefilter 102 ofFIG. 3 can be adjusted to smooth out the steps. - In some embodiments, each one of the primary plurality of
vertical Hall elements vertical Hall elements - The electronically parallel arrangement can be accomplished in two different ways. In a first parallel coupling, only output signals of each adjacent pair of the plurality of
vertical Hall elements 123 are coupled in parallel. In the first parallel coupling, drive signals provided to each one of the plurality ofvertical Hall elements 123 in an adjacent pair of vertical Hall elements can be different. In particular, for embodiments that use chopping, the different drive signals can be at different chopping phases at any time. - In a second parallel coupling, output signals of each adjacent pair of the plurality of
vertical Hall elements 123 are coupled in parallel, and also the drive signals to each adjacent pair of the plurality ofvertical Hall elements 123 are coupled in parallel. - In yet another parallel arrangement, output signals from each adjacent pair of the plurality of
vertical Hall elements 123 are summed at a subsequent amplifier, with or without parallel drive signals to thevertical Hall elements 123. - It should be appreciated that, with either electronically parallel coupled arrangement of the vertical Hall elements, output signal with higher signal to noise ratios are generated by each parallel pair of vertical Hall elements, higher than that which would be generated by any one vertical Hall element. Thus, the
magnetic field sensor 120 can achieve higher signal-to-noise ratios than themagnetic field sensors FIG. 4 or 5. - While the plurality of
vertical Hall elements 123 is shown to include parallel pairs of vertical Hall elements, in other embodiments, there can be parallel groups of vertical Hall elements, each parallel group having two or more geometrically parallel vertical Hall elements. - Referring now to
FIG. 7 , amagnetic field sensor 130 includes asemiconductor substrate 131 having a planar surface 131 a. Themagnetic field sensor 130 also includes a plurality ofvertical Hall elements 133. The plurality ofvertical Hall elements 133 includes, as a primary plurality of vertical Hall elements, primaryvertical Hall elements vertical Hall elements 133 also includes, as a secondary plurality of vertical Hall elements, secondaryvertical Hall elements separate implant regions - Each one of the primary vertical Hall elements and each one of the secondary vertical Hall elements includes a respective plurality of vertical Hall element contacts. Each plurality of primary vertical Hall elements contacts and each plurality of secondary vertical Hall element contacts is arranged in a respective line. The lines of primary and secondary vertical Hall element contacts are arranged in a pattern representative of a portion of polygonal shape, here a portion of a hexagon. Each one of the lines of the secondary vertical Hall element contacts can be geometrically parallel to a respective line of the primary vertical Hall element contacts. However, in other embodiments, each line of secondary vertical Hall elements can be rotated in relation to a respective line of primary vertical Hall elements. The rotation can be small, for example, 0.1 degrees, or the rotation can be large, for example thirty degrees.
- Each one of the primary plurality of
vertical Hall elements vertical Hall elements vertical Hall elements 133 are indicated as asignal 133 a. Thesignal 133 a can be similar to thedifferential signal 72 a, 72 b ofFIG. 3 and similar to thesignal 103 a ofFIG. 4 , the signal 113 a ofFIG. 5 , and the signal 123 a ofFIG. 6 . - The
magnetic field sensor 130 can also include an electronic circuit 140 disposed on the planar surface 131 a and coupled to each one of the plurality ofvertical Hall elements 133. The electronic circuit 136 is configured to generate anoutput signal 140 a. Themagnetic field sensor 130 can also include apattern completion generator 142 coupled to receive theoutput signal 140 a and configured to generate an output signal 142 a indicative of the angle of the projected component of the magnetic field. The electronic circuit 140 can be the same as or similar to that shown above in conjunction withFIG. 3 , wherein theCVH sensing element 72 is replaced by the plurality ofvertical Hall elements 133. - The electronic circuit 140 and the
pattern completion generator 142 are both electronic circuits disposed upon thesubstrate 131, and both together are referred to herein as an electronic circuit. - In operation, in some embodiments, each one of the plurality of
vertical Hall elements 133 can be processed by the electronic circuit 140 sequentially, resulting in a pattern of six sequential samples within thesignal 133 a. Unlike themagnetic field sensor 70 ofFIG. 3 , for which vertical Hall elements within theCVH sensing element 72 overlap and share vertical Hall element contacts, here, the plurality ofvertical Hall elements 133 do not share vertical Hall element contacts. It will become apparent from discussion below in conjunction withFIG. 9 that such an arrangement tends to generate an output signal that has fewer and larger steps than theoutput signal 52 ofFIG. 2 . However, thefilter 102 ofFIG. 3 can be adjusted to smooth out the steps. - In some embodiments, each one of the primary plurality of
vertical Hall elements vertical Hall elements signal 133 a. - As described above in conjunction with
FIG. 6 , the electronically parallel arrangement can be accomplished in different ways. In a first parallel coupling, only output signals of each adjacent pair of the vertical Hall elements are coupled in parallel. In the first parallel coupling, drive signals provided to each one of the vertical Hall elements in an adjacent pair of vertical Hall elements can be different. In particular, for embodiments that use chopping, the different drive signals can be at different chopping phases at any time. - In a second parallel coupling, output signals of each adjacent pair of the vertical Hall elements are coupled in parallel, and also the drive signals to each adjacent pair of the vertical Hall elements are coupled in parallel.
- In other embodiment, signals from lines of the primary and secondary vertical Hall elements can be combined at a subsequent amplifier.
- It should be appreciated that, with either electronically parallel arrangement of the vertical Hall elements, output signals generated by each parallel pair of vertical Hall elements are larger than that which we would be generated by any one vertical Hall element. Thus, the
magnetic field sensor 130 can achieve higher signal-to-noise ratios than themagnetic field sensors FIG. 4 or 5. - Unlike the magnetic field sensors of
FIGS. 4-6 , the plurality ofvertical Hall elements 133 is representative of only a portion of a polygonal shape. However, as described above in conjunction withFIG. 4 , the plurality ofvertical Hall elements 133 can be used to deduce other output signals as may be generated by vertical Hall elements that would otherwise form missing sides of the polygonal shape. Referring briefly toFIG. 6 , it will be understood that vertical Hall elements on opposite sides of the hexagonal shape have opposite output signals (i.e., signal values) but of the same amplitude when themagnetic field sensor 120 ofFIG. 6 experiences a magnetic field in the plane of thesurface 121 a. Thus, if a pair ofvertical Hall elements FIG. 7 is like a pair ofvertical Hall elements FIG. 6 , then a signal that would otherwise be generated by a pair ofvertical Hall elements FIG. 6 , counterparts of which are not present inFIG. 7 , can be deduced or calculated by generating another signal as an opposite of the signal generated by the pair ofvertical Hall elements vertical Hall elements 133 is representative of only a portion of a polygonal shape, for example, half of a hexagon, electronic magnetic field signals that would otherwise be generated by the other half of the hexagon, which is not present, can be calculated from the electronic magnetic field signals generated by the vertical Hall elements that are present. - To this end, in order to represent a complete polygon, the
pattern completion generator 142 completes the hexagonal pattern by deducing or calculating electronic signals from those within theoutput signal 140 a, which calculated electronic signals are not directly generated by the plurality ofvertical Hall elements 133. - While the plurality of
vertical Hall elements 133 is shown to include parallel pairs of vertical Hall elements, in other embodiments, there can be parallel groups of vertical Hall elements, each parallel group having two or more geometrically parallel vertical Hall elements. - Comparing the
magnetic field sensor 130 to themagnetic field sensor 120 ofFIG. 6 , because themagnetic field sensor 130 only generates the output signals 133 a from three parallel pairs of vertical Hall elements and calculates other signals to represent a complete polygonal shape of vertical Hall elements, themagnetic field sensor 130 can achieve an indication of the angle of the magnetic field faster than themagnetic field sensor 120 ofFIG. 6 . - Referring now to
FIG. 7A , amagnetic field sensor 150 is similar to themagnetic field sensor 130 ofFIG. 7 . However, themagnetic field sensor 150 includes a plurality ofvertical Hall elements 153 that are representative of a different portion of a polygonal shape than the plurality ofvertical Hall elements 133 ofFIG. 7 . Nevertheless, elements of and function of themagnetic field sensor 150 will be understood from the discussion above in conjunction withFIG. 7 . - Referring now to
FIG. 8 , amagnetic field sensor 170 is also similar to themagnetic field sensor 130 ofFIG. 7 . However, themagnetic field sensor 170 includes a plurality of vertical Hall elements 173 having only threevertical Hall elements electronic circuit 176 and apattern generator 178 can be the same as or similar to those described above in conjunction withFIG. 7 . Elements of and function of themagnetic field sensor 170 will be understood from the discussion above in conjunction withFIG. 7 . - Referring now to
FIG. 8A , amagnetic field sensor 190 is also similar to themagnetic field sensor 150 ofFIG. 7A . However, themagnetic field sensor 170 includes a plurality ofvertical Hall elements 193 having only threevertical Hall elements vertical Hall elements 193 does not include a secondary plurality of vertical Hall elements. Anelectronic circuit 196 and apattern generator 198 can be the same as or similar to those described above in conjunction withFIG. 7 . Elements of and function of themagnetic field sensor 190 will be understood from the discussion above in conjunction withFIGS. 7 and 7A . - While examples above show six (or twelve) vertical Hall elements with lines of vertical Hall element contacts arranged in hexagonal polygonal shapes, in other embodiments, other numbers of vertical Hall elements can be arranged with vertical Hall element contacts arranged in lines representative of other polygonal shapes having any number of sides greater than three sides.
- While examples above show three (or six) vertical Hall elements with lines of vertical Hall element contacts arranged in half of hexagonal polygonal shapes, in other embodiments, other numbers of vertical Hall elements can be arranged with vertical Hall element contacts arranged in lines representative of other portions of polygonal shapes, for example, three quarters of a polygonal shape.
- While vertical Hall elements having five vertical Hall element contacts are shown in examples above, in other embodiments, each vertical Hall element can have more than five or fewer than five vertical Hall element contacts.
- Referring now to
FIG. 9 is agraph 210 is similar to thegraph 50 ofFIG. 2 . Thegraph 50 has a horizontal axis with a scale in units of vertical Hall element position, n, around a polygonal arrangement of vertical Hall elements, for example, around the plurality ofvertical Hall elements 103 ofFIG. 4 . Thegraph 210 also has a vertical axis with a scale in amplitude in units of millivolts. - The
graph 210 includes asignal 212 representative of output signal levels from the plurality of vertical Hall elements of 102 a, 102 b, 102 c, 102 d, 102 e, 102 f ofFIG. 4 taken sequentially when in the presence of a magnetic field, stationary and pointing in a direction of sixty degrees. - In
FIG. 9 , a maximum positive signal is achieved from one of the sixvertical Hall elements magnetic field 16 ofFIG. 1 , such that the line of vertical Hall element contacts (e.g., five contacts) of the vertical Hall element is also perpendicular to the magnetic field. - A
sine wave 214 is provided to more clearly show the ideal behavior of thesignal 212. The sine wave can be generated by thefilter 102 ofFIG. 3 . - The
signal 214 can have variations due to vertical Hall element offsets, which tend to somewhat randomly cause element output signals to be too high or too low relative to thesine wave 214, in accordance with offset errors for each element. The offset signal errors are undesirable. In some embodiments, the offset errors can be reduced by the use of chopping described above. Chopping, as described above in conjunction withFIG. 4 , will be understood to be a process by which vertical Hall element contacts of each vertical Hall element are driven in different configurations and signals are received from different ones of the vertical Hall element contacts of each vertical Hall element to generate a plurality of output signals from each vertical Hall element. The plurality of signals can be arithmetically processed (e.g., summed or otherwise averaged) resulting in a signal with less offset. An offset generated by the vertical Hall elements induces non linearity in the sinusoidal signal (see, e.g.,FIGS. 2 and 9 ) that can be further reduced with a filter (not shown) centered at or near the sinusoidal frequency. - Groups of contacts of each vertical Hall element can be used in a chopped arrangement to generate chopped output signals from each vertical Hall element. Thereafter, a new group of adjacent vertical Hall element contacts can be selected (i.e., a new vertical Hall element). The new group can be used in the chopped arrangement to generate another chopped output signal from the next group, and so on.
- Each step of the
signal 212 can be representative of a chopped output signal from one respective group of vertical Hall element contacts, i.e., from one respective vertical Hall element. However, in other embodiments, no chopping is performed and each step of thesignal 212 is representative of an unchopped output signal from one respective group of vertical Hall element contacts, i.e., from one respective vertical Hall element. Thus, thegraph 212 is representative of a CVH output signal with or without the above-described grouping and chopping of vertical Hall elements. - It will be understood from discussion above in conjunction with
FIG. 3 , that a phase of the signal 212 (e.g., a phase of the signal 214) can be found and can be used to identify the pointing direction of the magnetic field relative to the polygonal pattern of vertical Hall elements. - While embodiments shown and described above indicate vertical Hall elements, in other embodiments, one or more of the vertical Hall elements can instead be a respective one or more magnetoresistance elements having respective axes of sensitivity aligned in the same directions as those of the above-described vertical Hall elements. Also, other types of magnetic field sensing elements are possible, so long as they have axis of sensitivity aligned in the same directions as those of the above-described vertical Hall elements. It will be apparent how to modify the electronic circuit of
FIG. 3 to use the various other types of magnetic field sensing elements. - All references cited herein are hereby incorporated herein by reference in their entirety.
- Having described preferred embodiments, which serve to illustrate various concepts, structures and techniques, which are the subject of this patent, it will now become apparent to those of ordinary skill in the art that other embodiments incorporating these concepts, structures and techniques may be used. Accordingly, it is submitted that that scope of the patent should not be limited to the described embodiments but rather should be limited only by the spirit and scope of the following claims.
Claims (39)
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US13/724,170 US8749005B1 (en) | 2012-12-21 | 2012-12-21 | Magnetic field sensor and method of fabricating a magnetic field sensor having a plurality of vertical hall elements arranged in at least a portion of a polygonal shape |
PCT/US2013/071635 WO2014099283A2 (en) | 2012-12-21 | 2013-11-25 | A magnetic field sensor and method of fabricating a magnetic field sensor having a plurality of vertical hall elements arranged in at least a portion of a polygonal shape |
KR1020157019065A KR102133195B1 (en) | 2012-12-21 | 2013-11-25 | A magnetic field sensor and method of fabricating a magnetic field sensor having a plurality of vertical hall elements arranged in at least a portion of a polygonal shape |
EP13802502.8A EP2932285A2 (en) | 2012-12-21 | 2013-11-25 | A magnetic field sensor and method of fabricating a magnetic field sensor having a plurality of vertical hall elements arranged in at least a portion of a polygonal shape |
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US11802922B2 (en) | 2021-01-13 | 2023-10-31 | Allegro Microsystems, Llc | Circuit for reducing an offset component of a plurality of vertical hall elements arranged in one or more circles |
WO2022225623A1 (en) * | 2021-04-23 | 2022-10-27 | Allegro Microsystems, Llc | An electronic circuit having vertical hall elements arranged on a substrate to reduce an orthogonality error |
US11555868B2 (en) | 2021-04-23 | 2023-01-17 | Allegro Microsystems, Llc | Electronic circuit having vertical hall elements arranged on a substrate to reduce an orthogonality error |
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KR102133195B1 (en) | 2020-07-13 |
US8749005B1 (en) | 2014-06-10 |
WO2014099283A2 (en) | 2014-06-26 |
KR20150097661A (en) | 2015-08-26 |
EP2932285A2 (en) | 2015-10-21 |
WO2014099283A3 (en) | 2014-10-09 |
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