An X-band hybrid MIC feedforward amplifier for low residual noise operation

A 10 GHz, 15 dB gain feedforward amplifier (FFA) is described whose design is primarily aimed at reducing residual phase noise. The two-module hybrid MIC construction incorporates GaAs MMICs and microstrip thin-film interconnects on alumina. For loop balance electronic gain control is achieved using dual gate distributed amplifiers, while phase control is accomplished with mechanical phase shifters and delay lines. Measurements of near carrier noise are made from 1 Hz to 6.4 MHz. In the flicker region the 1 Hz intercept is -110 dBc/Hz, with an approximate corner frequency around 30 KHz at -160 dBc/Hz.