Signal Processor Implementation of a Low-Pass/High-Pass IIR Digital Filter with Variable Cutoff Frequency

A simple tuning scheme that shifts the cutoff frequency of the start-up half-band filter to the desired location has been introduced recently. In this paper, the approximation of the tuning scheme is derived in a manner that makes this scheme suitable for fixed-point and signal processor implementation. The effects of the approximation error to the filter frequency response are analyzed. The measured frequency responses for the example low-pass filters implemented in the signal processor demonstrate the real-time application of the proposed method