Low noise high stability FM transmitter

摘要

An FM transmitter is disclosed wherein a solid state microwave source at a first frequency is frequency modulated with a baseband signal, and a second such source at a different frequency is frequency modulated with the baseband signal inverted. Each of the modulated carriers is frequency doubled and input to a mixer. The output of the mixer is a carrier, having a frequency which is twice the difference of the two microwave frequencies, and frequency modulated by the baseband signal. An automatic frequency control circuit inputs equal and opposite control voltages to the two microwave sources.