COMPUTER-AIDED-DESIGN OF QUARTZ-CRYSTAL OSCILLATORS

The latest development of a simulation program designed for quartz cry stal oscillator analysis is presented in this paper, The simulator bei ng developed uses the full nonlinear Barkhausen criterion method. It c onsists of finding the frequency w(0) and the amplitude u(0) which nul lify both the real and imaginary parts of a characteristic complex pol ynomial P(u,jw) describing the oscillator behavior. Most of the nonlin earities come from the amplifying transistor described by using large signal admittance parameters y(u) obtained by means of an analog circu it simulator (SPICE), This paper presents the method used to derive an d code the characteristic polynomial coefficients, This method has bee n successfully implemented for a Colpitts oscillator and is currently being used to build an oscillator library covering the most widely use d structures, The validity and the predictive power of the model have been checked experimentally and the comparison between experimental re sults and simulation is presented and discussed.