Phase noise spectra analysis for LC oscillators

This paper presents an analytical solution of the phase noise spectra for LC oscillators. Modeling noisy input processes as current impulse injections to the circuit, a linearized phase noise model is obtained by the Taylor series expansion method. For this linearized model, an analytic expression of the impulse sensitivity function (ISF) is derived. This is a new method to obtain ISF for a class of LC oscillators. Then we analyze for oscillator´s output power spectra density (PSD) and we show that the two widely publicized methods presented in Vanassche et al. (2003) and Demir (2002) produce equal results for the oscillator´s phase noise spectrum with white noise source.