Filter Vs. IIR Filter

7EngMsr Essay 02

Alistair Naidoo

Naidoa

171371

IIR filters vs FIR filters

Introduction

This essay will look at the differences of two filters, the infinite impulse response (IIR) and the finite impulse response (FIR). Each filter will be observed and will be discussed how they operate differently to each other. Each filter has its own unique characteristics in the filtration of signal. Each filter has its advantages and disadvantages, each filter operates differently and in turn causes different results when modulating a signal.

Figure 1- FIR and IIR filters, Picture taken from Google images.
Infinite impulse response

The infinite impulse response (IIR) filter is infinite because there is feedback in the filter. When there is an input of an impulse, the output of that impulse goes on indefinitely. The IIR filter is “distinguished by having an impulse response which does not become exactly zero past a certain point, but continues indefinitely” (wikipedia). The IIR filter

Biquads are an abbreviation for biquadratic and means in the Z domain, its transfer function is the ratio of two quadratic functions. Biquad is a digital filter that is a second-order recursive linear filter. The biquad contains two poles and two zeros. IIR filters are not stable and high-order IIR filters become extremely sensitive to quantization of their coefficients. There not much of a problem with the first and second-order filters, only higher-order filters are implemented as serially-cascaded biquad sections circle for it to become stable. IIR filters can recreate analog filter responses very accurately. Digital IIR filters are based on well-known analog filters such as The Butterworth filter, Chebyshev filter and the Elliptic