An effective noise-reduction scheme for microwave amplifiers

An effective noise cancellation scheme, based on feedforward techniques after cancellation of the signal carrier, is presented. Experimental characterization of a proof-of-concept system applied to a 10 GHz linear amplifier yielded up to 20 dB of noise reduction for offset frequencies smaller than 100 kHz. The system described in this paper allows reducing both white and flicker noise. A thorough analysis of the canceling mechanisms supports the measurement results and allows considerations of the limits of the scheme.