Microwave frequency synthesizer with a frequency offset generator.

摘要

A phase lock/frequency control loop includes a voltage-controlled oscillator (10) operating within a predetermined microwave frequency band and phase-locked to a reference oscillator (24) operating at a reference frequency below microwave frequencies. An offset loop signal is developed by an offset mixer (12) heterodyning the voltage-controlled oscillator (10) output signal with an offset microwave signal from an offset generator (14) whose frequency is located at the center of the predetermined microwave frequency band of the voltage controlled oscillator (10) to form a signal at an intermediate frequency (I.F.) within the frequency range of a programmable digital frequency divider (20). A phase/frequency detector (26) produces an error signal having a magnitude representative of the difference between the output from the divider (20) and a reference signal from a reference oscillator (24). The polarities of the error signal supplied, through an amplifier (30) and filter (32) to the voltage controlled oscillator (10) are set in accordance with whether the frequency commanded by a decoder (22) controlling the divider (20) is above or below the offset frequency. The signal frequency offset technique increases the frequency range of the indirect frequency synthesizer to twice the highest operating frequency of the programmable digital frequency divider.