A single-crystal oscillator comprising a single transistor and a capacitor divider connected in a feedback path, which includes the crystal input and output ports, between the collector and base of the transistor, thereby to provide a low-impedance input port to the crystal. The impedance of the crystal...http://www.google.de/patents/US4520326?utm_source=gb-gplus-sharePatent US4520326 - Single-stage oscillator having low-impedance feedback port
