The new estimation method using harmonic distortion in oscillator is proposed. This new estimation method includes circuit non-linearity effect in oscillator whereas the traditional Leeson’s model doesn’t. The proposed model relates the circuit non-linearity to the phase noise in oscillator. To verify the proposed model experimentally, passive buffer used oscillator topology is proposed. And, to implement the proposed oscillator, a commercial InGap/GaAs HBT foundry is used. The experimental result justifies the proposed model including circuit non-linearity effect. Moreover, the proposed oscillator has excellent Figure Of Merit (FOM) among the oscillators implemented by InGap/GaAs HBT.
In appendix, 40 GHz and 21GHz MMIC push-push oscillators which have small size, high output power and excellent F.O.M. are presented. These push-push oscillators utilize the embedded frequency doubling mechanism of cross coupled oscillator. A commercial InGaP/GaAs HBT process which provides 30 GHz $f_T$ transistor is used for the 40GHz oscillator implementation, and a commercial InGaP/GaAs HBT process which provides 66 GHz $f_T$ transistor is used for the 21GHz VCO implementation. The output power of the 40GHz push-push oscillator has -7.23dBm, which is very high output power among the push-push oscillators whose output frequency is over the cutoff frequency of the device. The 21GHz VCO has 1.7dBm output power and excellent F.O.M.
