Phase noise calculation technique using time varying model

All oscillators are periodically time varying systems, so to accurate phase noise calculation and simulation, time varying model should be considered. Phase noise is an important characteristic of oscillator design. It defined as the spectral density of the oscillator spectrum at an offset from the center frequency of the oscillator relative to the power of the oscillator. In this paper we study linear time invariant (LTI) and linear time variant (LTV) model´s for calculating phase noise, moreover we proposed in simple method for Impulse Sensitivity Function (ISF) calculation. This method is simpler than other methods and we can easily simulation ISF. The simulation results show that the proposed method almost is good.