Effect of high frequency substrate noise on LC-VCOs

This paper presents an experimental analysis of the performance degradation of an LC-Voltage Controlled Oscillator (LC-VCO) produced by high frequency noise present in the substrate. The spurs observed are shown to be caused by a frequency pulling mechanism. Based on the theory of injection locked oscillators, a new analytical model to predict the behavior of the LC-VCO under the effect of high frequency substrate noise is presented. The analytical model, which is successfully compared with experimental measurements on a 7 GHz LC-VCO, provides rapid intuition on the relation between spurs and circuit parameters.