Ftd: frequency to time domain conversion for reduced-order interconnect simulation

Model order reduction is an invaluable tool for solving part of the interconnect simulation problem, but an equally important problem is to interface these frequency-domain representations with the discrete time domain models that are used for nonlinear transient simulation. Various recursive convolution methods have been proposed which provide an exact solution to this interface problem under the assumption of piecewise linear voltage waveforms. This paper proposes a frequency to time-domain conversion algorithm, ftd (frequency to time domain), that represents a seemingly optimal form of recursive convolution. We demonstrate that ftd provides exact accuracy for piecewise linear inputs. Moreover, ftd is algorithmically straight-forward and simple to implement for a specific application.