Transposed gain microwave oscillators with low residual flicker noise

This paper describes the design of two low noise microwave oscillators operating at 7.6 GHz. These oscillators use room temperature sapphire resonators operating in the TE₀₁δ mode which demonstrate unloaded Q´s of 44,000. Silicon transposed gain amplifiers are used to produce near-flicker-free gain. Oscillators with flicker noise corners around 1 kHz and a phase noise of -131 dBc/Hz at 10 kHz offset are demonstrated. This is within 5.5 dB of the theoretically predicted minimum noise. Further improvements of 30 dB are expected using related techniques