VCO phase noise model at high RF frequencies and sub90 nm processes

We present a generic precise modular calculation method for the estimation of phase noise of LC oscillators. We expand the idea of nearly sinusoidal voltage output by analyzing the output characteristic with a linear system of equations, which are provided by a Fourier Series Expansion. With this procedure we increase the accuracy of the simulation at a low computational cost. The calculation is based on the devices' nonlinear responses on the fundamental sinusoid and on computing the high harmonics response through a linear set of equations, considering the nonlinearities known. In that way we achieve higher accuracy avoiding the solution of a nonlinear system. Various effects (i.e. variable parallel resistance) can be included, thus increasing the accuracy further. Upon voltage characteristic computation, Hajimiri's phase noise calculation method is employed to procure the final phase noise.