WO1996025791A1 - Amplifiers - Google Patents
Amplifiers Download PDFInfo
- Publication number
- WO1996025791A1 WO1996025791A1 PCT/GB1996/000343 GB9600343W WO9625791A1 WO 1996025791 A1 WO1996025791 A1 WO 1996025791A1 GB 9600343 W GB9600343 W GB 9600343W WO 9625791 A1 WO9625791 A1 WO 9625791A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- amplifier
- harmonic
- order
- order intermodulation
- injected
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/32—Modifications of amplifiers to reduce non-linear distortion
- H03F1/3205—Modifications of amplifiers to reduce non-linear distortion in field-effect transistor amplifiers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/32—Modifications of amplifiers to reduce non-linear distortion
- H03F1/3223—Modifications of amplifiers to reduce non-linear distortion using feed-forward
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/32—Modifications of amplifiers to reduce non-linear distortion
- H03F1/3241—Modifications of amplifiers to reduce non-linear distortion using predistortion circuits
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2201/00—Indexing scheme relating to details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements covered by H03F1/00
- H03F2201/32—Indexing scheme relating to modifications of amplifiers to reduce non-linear distortion
- H03F2201/3206—Multiple channels are combined and amplified by only one amplifier
Definitions
- This relates to amplifiers and, in particular, to methods of reducing the third order intermodulation product levels in non-linear MESFET amplifiers.
- This method is based on the injection of a harmonic signal to the amplifier system and is applicable to other three-terminal active devices such as HEMTs and HBTs.
- a common performance parameter of amplifiers used in communication systems is the effect of nonlinearity on the amplifier performance.
- the intermodulation products are regarded as the most troublesome distortion in communication system amplifiers.
- Many attempts have been made to reduce intermodulation products levels. Beside linearisation techniques, other approaches such as optimising the load impedance or terminating the second harmonic voltage in a short circuit have been employed for this purpose. Applying the above techniques to improve intermodulation levels may prevent the designer from using the full capability of the active device or alternatively the required circuitry may be rather complex, expensive and large in size.
- the use of negative feedback methods for reducing the intermodulation distortion in non-linear amplifiers causes a reduction in the amplifier gain, and its alternative, the feedforward technique requires a second high performance amplifier closely matched to the main amplifier.
- the third order intermodulation product is the most dominant intermodulation distortion in non-linear amplifiers which are employed in communication systems.
- an amplifier into which a correction signal comprising the second order harmonic of the source signal is fed, the amplitude and phasing of the correction signal being selected at least partially to compensate for distortion generated in said amplifier.
- the method is based on using non-linearity of the amplifier to cancel out the third order intermodulation product.
- the second order harmonics of the source signals are injected into the amplifier as well as the fundamental signals.
- Non-linearity of the amplifier causes interaction between the source signals and their injected second order harmonics. This interaction results in additional signals at the output of the amplifier at the third order intermodulation frequencies.
- there are components of the third order intermodulation product due to the interaction between the fundamental signals.
- Figure 1 is an amplifier circuit showing injection of the second harmonics
- FIGS. 2 to 4 and 6 are illustrative graphs
- Figure 5 is a circuit diagram illustrating an alternative embodiment of the invention
- Figures 7 - 10 are oscilloscope traces of practical measurements.
- a simplified non-linear model is used for the MESFET transistor.
- the transconductance is regarded as non-linear as it is the dominant nonlinearity in class B amplifiers. This nonlinearity can be approximated by a three-term power series expansion for the drain current, i d , as
- v in . is the gate to source voltage.
- the second term in Eq. 3 is the result of interaction between fundamental signals.
- the first and the third terms are the consequence of injection of the second harmonics into the amplifier.
- the third term in the above equation is small in comparison to the two other terms and can be ignored.
- the fundamental input signals are arbitrarily chosen at frequencies 2.5 GHz and 2.51 GHz.
- the results of this investigation is shown in Figure 2 and 3.
- a typical fundamental and third order intermodulation product power versus frequency plot is drawn in Figure 2 when no external second harmonic is injected to the circuit. (This drawing shows a dip in the intermodulation curve. This dip is a result of cancellation between different nonlinearities namely transconductance and drain conductance).
- the simulated effect of the injected second harmonic level on the third order intermodulation at lower power levels (below the dip region in the third order intermodulation curve) is shown in Figure 3.
- the second harmonic signal may be injected at ei er the input or output of the amplifier. It is also possible to provide this harmonic at the input by feeding back the second harmonic generated by the nonlinearity of the amplifier from output to the input and the same benefit is obtained ( Figure 5 and 6). This also illustrates that the second harmonic technique reduces both terms of the third order intermodulation product simultaneously.
- the mathematical analysis and CAD simulation of the performance of a MESFET non-linear amplifier reveal that the level of the third order intermodulation product can be reduced by generating and injecting the second harmonics of the input signals.
- the third order intermodulation levels at lower or higher power level or indeed at the IdB compression point can be reduced substantially by injecting the second harmonic signals with appropriate phase and amplitude into the amplifier.
- Non-linear simulation predicts a reduction of more than 30 dB in the third order intermodulation levels.
- the required second harmonic signal can be injected to either input or output of the amplifier. It is also possible to provide this signal through a feedback path which only feeds back the generated second harmonics from output to the input of the amplifier.
- the absence of trade-off between the gain and the third order intermodulation level (and higher efficiency as a result), simple circuitry and small size are among other advantages of this technique.
- two 500MHz signals separated by 1MHz were fed into an MESFET amplifier together with the appropriately phased second harmonic of one signal obtained using a diode doubler. Adjustment of the level of the second harmonic showed a reduction in the corresponding their order intermodulation sideband by 19dB without significant change in the fundamental levels and the other intermodulation sideband.
- Figures 7 and 8 are traces respectively showing the intermodulation spectrum with and without the technique applied.
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP96902382A EP0809881A1 (en) | 1995-02-15 | 1996-02-15 | Amplifiers |
JP8524767A JPH11500276A (en) | 1995-02-15 | 1996-02-15 | amplifier |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9502894.0 | 1995-02-15 | ||
GBGB9502894.0A GB9502894D0 (en) | 1995-02-15 | 1995-02-15 | Amplifiers |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1996025791A1 true WO1996025791A1 (en) | 1996-08-22 |
Family
ID=10769593
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1996/000343 WO1996025791A1 (en) | 1995-02-15 | 1996-02-15 | Amplifiers |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0809881A1 (en) |
JP (1) | JPH11500276A (en) |
GB (1) | GB9502894D0 (en) |
WO (1) | WO1996025791A1 (en) |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2001005042A1 (en) * | 1999-07-13 | 2001-01-18 | Koninklijke Philips Electronics N.V. | A two-port with a frequency-dependent network |
WO2001045279A1 (en) * | 1999-12-17 | 2001-06-21 | Nokia Corporation | Linearisation method and signal processing device |
GB2407931A (en) * | 2003-11-04 | 2005-05-11 | Agilent Technologies Inc | Power amplifier with improved linearity |
EP1253708A3 (en) * | 2001-04-27 | 2006-07-19 | Hitachi Kokusai Electric Inc. | Distortion canceling circuit |
US7123073B2 (en) | 2002-03-28 | 2006-10-17 | Matsushita Electric Industrial Co., Ltd. | Amplifier and frequency converter |
US7298205B2 (en) | 2003-09-24 | 2007-11-20 | Matsushita Electric Industrial Co., Ltd. | Amplifier and frequency converter |
EP1562286A3 (en) * | 2004-02-09 | 2008-03-05 | Sony Ericsson Mobile Communications Japan, Inc. | Distortion compensating device and power amplifying device with distortion compensating function |
CN101388649B (en) * | 2008-10-13 | 2010-08-11 | 电子科技大学 | Low non-linear power amplifier |
US20110194979A1 (en) * | 2007-03-12 | 2011-08-11 | Fabrico Technology, Inc. | Modulated magnetic permeability sensing assays |
EP2983454A1 (en) * | 2014-08-08 | 2016-02-10 | Nxp B.V. | Single tone RF signal generator |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5172072A (en) * | 1991-09-06 | 1992-12-15 | Itt Corporation | High efficiency harmonic injection power amplifier |
JPH0722850A (en) * | 1993-06-30 | 1995-01-24 | Fujitsu Ltd | Linear amplifier |
JPH0722849A (en) * | 1993-06-30 | 1995-01-24 | Fujitsu Ltd | Linear amplifier |
-
1995
- 1995-02-15 GB GBGB9502894.0A patent/GB9502894D0/en active Pending
-
1996
- 1996-02-15 JP JP8524767A patent/JPH11500276A/en active Pending
- 1996-02-15 WO PCT/GB1996/000343 patent/WO1996025791A1/en not_active Application Discontinuation
- 1996-02-15 EP EP96902382A patent/EP0809881A1/en not_active Ceased
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5172072A (en) * | 1991-09-06 | 1992-12-15 | Itt Corporation | High efficiency harmonic injection power amplifier |
JPH0722850A (en) * | 1993-06-30 | 1995-01-24 | Fujitsu Ltd | Linear amplifier |
JPH0722849A (en) * | 1993-06-30 | 1995-01-24 | Fujitsu Ltd | Linear amplifier |
US5455538A (en) * | 1993-06-30 | 1995-10-03 | Fujitsu Limited | Linear amplifier for amplifying a composite signal of plural frequency components |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 95, no. 001 * |
Cited By (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6424226B1 (en) | 1999-07-13 | 2002-07-23 | Koninklijke Philips Electronics N.V. | Two-port with a frequency-dependent network |
WO2001005042A1 (en) * | 1999-07-13 | 2001-01-18 | Koninklijke Philips Electronics N.V. | A two-port with a frequency-dependent network |
WO2001045279A1 (en) * | 1999-12-17 | 2001-06-21 | Nokia Corporation | Linearisation method and signal processing device |
US6922552B2 (en) | 1999-12-17 | 2005-07-26 | Nokia Corporation | Linearization method and signal processing device |
EP1253708A3 (en) * | 2001-04-27 | 2006-07-19 | Hitachi Kokusai Electric Inc. | Distortion canceling circuit |
US7123073B2 (en) | 2002-03-28 | 2006-10-17 | Matsushita Electric Industrial Co., Ltd. | Amplifier and frequency converter |
US7298205B2 (en) | 2003-09-24 | 2007-11-20 | Matsushita Electric Industrial Co., Ltd. | Amplifier and frequency converter |
GB2407931A (en) * | 2003-11-04 | 2005-05-11 | Agilent Technologies Inc | Power amplifier with improved linearity |
EP1562286A3 (en) * | 2004-02-09 | 2008-03-05 | Sony Ericsson Mobile Communications Japan, Inc. | Distortion compensating device and power amplifying device with distortion compensating function |
US20110194979A1 (en) * | 2007-03-12 | 2011-08-11 | Fabrico Technology, Inc. | Modulated magnetic permeability sensing assays |
US8927260B2 (en) * | 2007-03-12 | 2015-01-06 | Fabrico Technology, Inc. | Anaylte detection system using an oscillating magnetic field |
CN101388649B (en) * | 2008-10-13 | 2010-08-11 | 电子科技大学 | Low non-linear power amplifier |
EP2983454A1 (en) * | 2014-08-08 | 2016-02-10 | Nxp B.V. | Single tone RF signal generator |
CN105375898A (en) * | 2014-08-08 | 2016-03-02 | 恩智浦有限公司 | Single tone rf signal generator |
US9571137B2 (en) | 2014-08-08 | 2017-02-14 | Nxp B.V. | Single tone RF signal generator |
Also Published As
Publication number | Publication date |
---|---|
GB9502894D0 (en) | 1995-04-05 |
EP0809881A1 (en) | 1997-12-03 |
JPH11500276A (en) | 1999-01-06 |
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