Effects of substrate on phase-noise of bipolar voltage-controlled oscillators

So far, there have been many studies addressing the effects of the substrate on silicon-based integrated RF passive components, but none of them has addressed to what extent the substrate influences RF front-end circuits and phenomena, such as noise-figure and phase-noise. In particular, there are many different models of spiral inductors on silicon, and even more substrate models of such inductors, all claiming to be representative of their onchip counterparts. When subjected to verification in a circuit environment, for example in LC oscillators, those models often predict a dramatically different circuit performance in terms of phase-noise, voltage-swing, loop-gain and tuning-range, for a given power consumption. Therefore, this aspect of model verification is presented in this paper, showing that the design trajectory of LC-oscillators depends to an excessively large extent on the inductor models used in the analysis. Also, it is shown that the phase-noise of a quasi-tapped oscillator is, contrary to common belief, not a monotonic function of substrate resistivity