Transposed flicker noise suppression in microwave oscillators using feedforward amplifiers

The authors describe the design of a low noise 7.6 GHz oscillator which achieves reduced transposed flicker noise by using a feedforward GaAs based power amplifier as the oscillator feedback amplifier, 20 dB noise suppression is demonstrated, at 12.5 kHz offset, in the oscillator when the error correcting amplifier is switched on. The phase noise in the error corrected version rolls off at (1/Δf)² at offsets >10 kHz. The phase noise performance, in the thermal noise region, is within 1 dB of the theoretical minimum