Frequency agile phase-locked loop synthesizer for a communications satellite

The paper describes an experimental frequency synthesizer designed for use on board a signal-processing communications satellite. The synthesizer combines wide bandwidth, fast frequency switching, and fine resolution with minimum parts count and power consumption. A phase-locked loop controls a Voltage Controlled Oscillator (VCO) at the output frequency. Switch selection of fixed downconversion local oscillators is employed to achieve wide bandwidth. Fine frequency resolution with fast switching is achieved by inserting a digitally-synthesized offset inside the loop with a single sideband modulator.