Quasiperiodic steady-state analysis of electronic circuits by a spline basis

Multitone Harmonic Balance (HB) is widely used for the simulation of the quasiperiodic steady-state of RF circuits. HB is based on a Fourier expansion of the waveforms. Unfortunately, trigonometric polynomials often exhibit poor convergence properties when the signals are not quasi-sinusoidal, which leads to a prohibitive run-time even for small circuits. Moreover, the approximation of sharp transients leads to the well-known Gibbs phenomenon, which cannot be reduced by an increase of the number of Fourier coefficients. In this paper we present alternative approaches based on cubic or exponential splines for a (quasi-) periodic steady state analysis.Furthermore, it is shown below that the amount of coding afford is negligible if an implementation of HB exists.