In one embodiment, a low-noise source includes: a signal source; a variable amplifier adapted to amplify an output signal from the signal source to provide an amplified signal; a feed-forward amplifier adapted to amplify the amplified signal to provide an amplified output signal; a phase noise measurement system adapted to provide a first feedback signal responsive to phase noise in the amplified output signal; and a processor adapted to control the amplification provided by the variable amplifier responsive to the feedback signal so as to minimize phase noise in the amplified output signal.