Dual frequency voltage controlled oscillator

摘要

A voltage controlled oscillator (10) operable on two widely separated frequency bands of 800 MHz and 1.9 GHz, for example. The two operable frequency modes are controlled by changing base bias voltages on at least two transistors with commonly connected emitters. A base circuit of each transistor is connected to an independent resonator and tuning element and shares a common feedback reactance. By increasing a base bias voltage of first transistor relative the a second transistor, an associated first base circuit is turned on and allowed to oscillate at a first frequency while a second base circuit is turned off preventing oscillation at a second frequency. Correspondingly, by decreasing the base bias voltage the first base circuit is turned off and the second base circuit is turned on. The transistors share a common collector connection and output providing either one of the two frequencies.