FREQUENCY GENERATING DEVICE UTILIZING A PHASE LOCKED LOOP INCLUDING A VOLTAGE CONTROL OSCILLATOR

A frequency generating device has a phase-locked loop that is operable to cause an associated VCO to lock at the arithmetic means of two input frequencies applied to the loop. By mixing the frequency of the VCO with the two input frequencies in separate mixers, the mixer outputs may be used as inputs to a phase detector. The output of the phase detector is then utilized to lock the VCO output to said arithmetic mean as the difference frequencies from the mixers are only equal at that particular mean value. However, by using dividers located between mixers and the phase detector inputs, it is possible to lock the VCO to some frequency other than the arithmetic mean so long as its value is somewhere between the two input frequencies.