Implementation and Performance Measurement of Q-Varying and r-Varying IIR Notch Filter for Bio-medical Application

Notch filters are extensively used to suppress the noise in biomedical application. Since the biosignals are very weak signals and having short duration, filters with high selectivity and better transient response are desirable. Transient response of notch filter increases with increase in quality factor and pole radius of notch filter. So, a different concept of IIR notch filters whose quality factor (Q) and pole radius (r) is varying with time have been implemented in this paper which results limiting the transient duration. The performance of these filters (with variable Q and r parameters) was compared with those notch filters that have constant Q and constant r parameters. The results revealed that the notch filters with variable quality factor and variable pole radius have better transient response as compared to the notch filters that have constant Q and constant r parameters. The performance of this Q-varying and r-varying IIR notch filters was also measured for the filtering of ECG signals corrupted by fixed frequency noise. The result shows that the Q-varying and r-varying IIR filter gives better performance over other conventional IIR notch filter.