SPICE aided crystal oscillator simulation

Abstract

Crystal oscillator (OX) simulation is connected with significant difficulties. The OX simulation is carried out on the base of its full (circuit) model, obtained by direct connection of components models at common equations set according to circuit topology. One of ways of simulation speed increasing is the way of replacement of complex full model by simple, approximate model (macromodel). As an approximate model, the known model of OX on two-pole with negative resistance can be used. In the given model, based on the high-Q resonator properties, the resonator drive circuit is represented as the two-pole and characterized by averaged through the period parameters. Change from differential parameters to averaged through the period parameters allow to reduce the differential equations order and considerably lower demands to computer power. Moreover, because of the high order of resonator quality factor, the approximate model gives practically the same accuracy of simulation as full model. Numerical methods are the most effective for solution of the first task and first step simulation can be performed at SPICE (or other EDA) environment