Fast phase noise analysis method for noise optimisation of oscillators

A novel fast phase noise analysis method is presented in this paper which can play an important role in both qualitative and quantitative carrier to noise (CNR) optimisation of oscillators. It is based on AC noise analysis in standard circuit simulators. One transient run is needed to obtain carrier power which is used to calculate the CNR. In seconds the total phase noise of oscillators bahaving linear or weakly non-linear is quantified together with all contributing noise sources. Results of the AC method (∼30 seconds simulation time) are compared with transient phase noise simulations of a SOA 3.6 GHz LC oscillator. Both methods match within 1 dB for open loop gains smaller than 1.8. Evaluation of a linear I/Q RC oscillator in production show that CNR predictions and measurements match within 1 dB.