Enhanced transposed gain microwave oscillators

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 -143 dBc/Hz at 10 kHz offset and -121 dBc/Hz at 1 kHz are demonstrated. This is within 3 dB of the theoretically predicted minimum noise. This performance is 12 dB better that in oscillators presented at the 1995 IEEE MTT conference and 1995 FCS conference. This improvement is achieved by using high level mixers