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.