A novel technique for automatic frequency control of microwave IMPATT oscillators

Abstract

A new technique for automatic frequency control (a.f.c.) of the IMPATT oscillator has been developed in the X-band (8–12GHz), using a cavity-type frequency discriminator. The error correction for the frequency of the oscillator is realized through a microprocessor delivering control signals to a current compensating circuit which automatically adjusts the required bias supply to the IMPATT diode. The stability characteristics of the a.f.c. controlled oscillator, studied in terms of the values of the Allan variance, shows that the frequency deviation of the locked oscillator may be reduced by a factor of 100 as compared to the freerunning oscillator. The system is found to be fast acting and capable of operation over a broad range of frequency changes, and is thus expected to be of great practical use.