Wideband IIR digital integrator and differentiator using curve fitting technique

In this paper, we propose an IIR design of wideband digital integrator and differentiator. We start our design with an IIR backward rectangular integrator. The response of the rectangular integrator is close to the ideal integrator only in the low frequency region. To improve the response, we connect an IIR filter in cascade with the backward integrator. The IIR filter is constructed using curve fitting toolbox of MATLAB as a ratio of two FIR functions. Integrator and differentiator thus obtained have response close to the ideal over entire Nyquist range of frequency with an error much less than what is reported in literature so far.