Abstract: A model of a device is generated. An input port of the device is stimulated with a large amplitude signal having a central frequency. A first port of the device is perturbed with a small amplitude signal tone. The small amplitude signal tone is at a frequency offset slightly from a harmonic of the central frequency. Spectral component frequencies of a resulting signal from the device are obtained to determine model coefficients for the device. At least some of the spectral component frequencies occur at frequencies offset slightly from harmonics of the central frequency.

Abstract: An improved circuit simulator for simulating the response of a circuit to a transient. The stimulating signal is represented by one or more carriers having time varying modulation envelopes. The simulator differs from a harmonic balance simulator in that the currents provided by each of the device subroutines include an additional term at each carrier frequency having the time dependency of the modulation envelope at that frequency. These additional current terms necessitate a time-domain solution of the simulation problem; however, the time steps are now determined by the time variation of the envelope instead of the time variation of the carrier. As a result, the number of time steps needed in the simulation is greatly reduced. The present invention may be implemented by modifying a conventional harmonic balance simulator. The modifications involve adding code to the various device routines to provide the current term corresponding to the modulation envelope.