IIR Filter
An infinite-impulse-response digital filter that uses feedback, allowing efficient frequency responses but introducing stability and phase considerations.
Signal Processing Context
An Infinite Impulse Response filter uses feedback, so its output depends on both current or past input samples and past output samples. This feedback can achieve sharp frequency responses with lower filter order than a comparable FIR design.
Measurement Boundary
IIR filters require stability and numerical-behavior analysis. Finite-precision arithmetic, coefficient quantization, phase response, and internal state can materially affect real implementations.