SIMULATION OF THE PHASE NOISE OF OSCILLATORS IN THE FREQUENCY-DOMAIN

A method for calculating the phase noise of oscillators in the frequen cy domain is outlined and its feasibility is demonstrated for a basic oscillator model. The small signal analysis usually used to compute th e noise behavior of amplifiers and mixers is numerically ill-condition ed for computing the oscillator noise in the vicinity of the carrier f requency. This is an inherent problem in the analysis of oscillator ci rcuits due to the lack of phase reference. We overcome this problem by using a perturbation theory around the steady state solution. By this way we calculate the phase noise in a numerically stable way. This me thod is applicable without any restrictions concerning the complexity of the oscillator circuits and the nature of the noise sources. Especi ally it is able to treat modulated or unmodulated white or 1/f(alpha) noise sources. We demonstrate the method by analysing a basic oscillat or circuit. The results are compared with a time-domain method [1].