Implementation and Applications of IIR Filters

IIR (Infinite Impulse Response) filters are fundamental components in digital signal processing, widely employed across multiple domains including audio processing, image processing, biomedical engineering, and seismology. In audio applications, IIR filters excel at tasks like audio enhancement and noise reduction through efficient recursive implementations using difference equations (e.g., y[n] = b0*x[n] + b1*x[n-1] - a1*y[n-1]). For image processing, these filters facilitate operations like image sharpening and noise removal via 2D convolution implementations with pole-zero placement algorithms. Biomedical engineering leverages IIR filters for biosignal analysis through specialized transfer function designs (e.g., Butterworth or Chebyshev responses) for ECG/EEG signal conditioning. Seismological applications utilize IIR filters for seismic waveform analysis with cascade structures providing precise frequency selectivity. Mastery of IIR filter implementation—including stability considerations, coefficient quantization effects, and realization structures (direct forms I/II, cascade, parallel)—is essential for digital signal processing professionals.