We have simulated the phase noise of a voltage controlled oscillator (VCO) using an RF circuit simulator, SpectreRF~TM (1). This simulator uses a variation of the periodic noise anlaysis first proposed by Okumura, et al (2). It computes the power spectral density of the noise as a function of frequency. By assuming that only white noise sources are present in the oscillator it is possible to derive a simple relationship between the level of the phase noise and the jitter. This excludes flicker noise from consideration, however since flicker noise is a low-frequency phenomenon, excluding it only affects the accuracy of the long-term jitter. We compared the jitter with measurement and found the error to be less than 2 dB. An AHDL model for the VCO that efficiently exhibits jitter in the time domain is included. The model was written in Verilog-A. This model can be used to determine the affect of VCO itter on a larger system, such as a phase-lockaed loop (PLL).
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