Accurate simulation of phase noise in oscillators

This paper describes a new method that calculates the phase noise power of an oscillator as a function of the offset frequency. Through the use of a sophisticated frequency selection method, the partial noise spectra of the different noise generating components can be constructed. An appropriate combination of these spectra results in the overall output phase noise spectrum. A number of solutions are discussed which improve the numerical accuracy and reduce the necessary CPU time. This new method is demonstrated with the phase noise evaluation of a 1.8 GHz CMOS VCO, and the results are compared with measurements. The difference is not larger than 1.3 dBc/Hz, which can be accounted for by the statistical fluctuations.