A method, apparatus and computer program product for determing a frequency response of a nonlinear microelectronic circuit includes simulating the behavior of the circuit over a broad frequency range by producing a plurality of periodic component signals, having respective noninterfering frequencies within the frequency range, as an input signal to the nonlinear microelectronic circuit. A time domain simulation of the behavior of the microelectronic circuit is then produced and followed by production of a frequency domain simulation from the time domain simulation once a steady-state condition has been reached. Only a single time domain simulation is required and it can be generated simultaneously for all frequencies in the desired range without the occurrence of second-order harmonic interferences. The plurality of periodic component signals are summed together and produced as a multifrequency input signal by initially determining respective frequencies (and amplitudes) for the component signals and then determining whether one or more of the frequencies, or second-order harmonics or intermodulation components of the frequencies, equals another of the frequencies to thereby cause interference among the plurality of periodic component signals. If an interference is present, then at least one of the frequencies is adjusted to reduce potential interferences among the plurality of periodic component signals and thereby obtain a new plurality of frequencies for the periodic component signals. These operations repeatedly performed to eliminate second-order interferences among the periodic component signals, before using the periodic component signals as an input signal.
|U.S. patent number
|Published - Sep 2 1997