Nonlinear analysis of phase noise in microwave oscillators using standard envelope transient technique

In this paper, a numerical technique for the determination of the phase-noise spectrum of free-running oscillators is presented. The technique is based on envelope transient and can be applied to any commercial simulator on which this analysis method is available. The main advantage of the technique is that it allows simulating the near carrier phase noise spectrum, including possible resonances. The elements providing the oscillator phase-noise spectrum are obtained from envelope-transient simulations of low-computational cost. Comparisons are performed between the presented technique and other existing techniques, such as the conversion-matrix approach. The technique has been successfully tested on the simulation of the near carrier phase noise spectrum of an oscillator circuit at 6.3 GHz.