Breitbandoszillator mit automatischer Vorspannungssteuerung

摘要

A bipolar negative resistance UHF oscillator having a voltage tunable resonator in its emitter circuit is operated at a fixed collector bias current and an RF detector is used as a convenient way to determine the RF current at which the oscillator is operating, by sensing the amplitude of the oscillator's output RF voltage across a constant load. An integrating error amplifier referenced to a desired detector output level responds to the actual detector output level to control the collector bias voltage for the oscillator and maintain the output of the oscillator at a fixed amplitude. Since the collector bias current is fixed, this keeps the operating point at fixed relation with respect to emitter cutoff. That relationship is chosen to be "just below" by initial selection of the constant collector bias current and the reference voltage used by the integrating error amplifier. The result is a VCO tunable over an octave with minimal phase noise, near maximum power output and immunity to temperature variations and shifts in oscillator device parameters.