Band Limited Impulse Invariance Method

We propose the band-limited impulse invariance method, which models a continuous-time LTI system in the discrete-time domain with high accuracy. A given system function in the Laplace domain is realized in the z-domain as a parallel connection of IIR and FIR filters. The IIR part is obtained by using the conventional impulse invariance method, whereas the FIR part is designed in such a way that it suppresses the aliasing occurring in the IIR filter. The FIR coefficients are derived analytically from a band-limited representation of the continuous-time impulse response. The accuracy of the discrete-time model is readily adjusted by the FIR length.