Reduced flicker noise in microwave oscillators using feedforward amplifiers

Transposed flicker noise removal is demonstrated in a 7.6 GHz microwave oscillator for offsets greater that 10 kHz. This is achieved by using a GaAs based feedforward power amplifier as the oscillation sustaining stage. 20 dB noise suppression is demonstrated at 12.5 kHz offset when the error correcting amplifier is switched on. The phase noise rolls-off at (1//spl Delta/F)/sup 2/ for offsets greater than 10 kHz and is therefore set by the thermal noise to within 0-2 dB of the theoretical minimum.