IIR (Infinite Impulse Response)

An IIR (Infinite Impulse Response) is a type of digital filter used in signal processing that responds to an input signal with an output that continues indefinitely. Unlike finite impulse response (FIR) filters, which depend only on current and past input values, IIR filters also use past output values. This feedback allows IIR filters to achieve desired filtering effects more efficiently, often with fewer calculations. They are widely used in audio, communications, and control systems to refine signals, remove noise, or extract specific features. Despite their efficiency, IIR filters require careful design to ensure stable and accurate performance.