Continuous-spectrum frequency-domain simulation of nonlinear systems

This paper describes an algorithm for frequency-domain simulation of nonlinear systems that, unlike harmonic balance, can handle signals with continuous frequency spectra. The algorithm is based on an orthogonal series expansion of band-limited signals in the frequency domain. Thus it is, in a sense, the dual approach to frequency-domain simulation with respect to harmonic balance, which relies on a orthogonal series expansion of the signals in the time domain. Numerical results obtained on a number of circuits, including a second-order delta-sigma modulator, indicate that this algorithm offers a viable approach to frequency-domain simulation of nonlinear systems in the presence of signals with continuous frequency spectra