Home of RF and Wireless Vendors and Resources

One Stop For Your RF and Wireless Need

FIR filter vs IIR filter

This page on FIR filter vs IIR filter describes difference between FIR filter and IIR filter .
FIR filter

FIR filter uses only current and past input digital samples to obtain a current output sample value. It does not utilize past output samples.Simple FIR equation is mention below.
y(n)= h(0)x(n) + h(1)x(n-1) + h(2)x(n-2) + h(3)x(n-3) + h(4)x(n-4) IIR filter
IIR filter uses current input sample value, past input and output samples to obtain current output sample value.Simple IIR equation is mention below.
y(n)= b(0)x(n) + b(1)x(n-1) + b(2)x(n-2) + b(3)x(n-3) + a(1)y(n-1) + a(2)y(n-2) + a(3)y(n-3)

Transfer function of FIR filter will have only zeros, need more memory, while transfer function of IIR filter will have both zeros and poles and will require less memory than FIR counterpart.

FIR filters are preferred due to its linear phase response and also they are non-recursive. Feedback is not involved in FIR, hence they are stable. IIR filters are not stable as they are recursive in nature and feedback is also involved in the process of calculating output sample values.

FIR filter consume low power and IIR filter need more power due to more coefficients in the design.

IIR filters have analog equivalent and FIR have no analog equivalent.

FIR filters are less efficient while IIR filters are more efficient.

FIR filters are used as anti-aliasing,low pass and baseband filters. IIR filters are used as notch(band stop),band pass functions.

FIR filter need higher order than IIR filter to achieve same performance. Delay is more than IIR filter. It has lower sensitivity than IIR filter. These are disadvantages of FIR filters.

FIR/IIR filter MATLAB Functions/Tools

fir1 function- It used to obtain FIR filter coefficients.
filter(chn,X) function- It is used to filter baseband data vector X with 'chn' filter coefficients
FDATOOL - Filter design and analysis tool
FIRRCOS function- Raised cosine FIR filter design
butter,bessel,cheby1,cheby2,ellip are IIR filters of various types.

MATLAB Source codes

FIR Filter
IIR Filter
Low Pass FIR

Low Pass FIR Filter Verilog

Low Pass FIR Filter

Useful Links

http://www.fourier-series.com/ - Simulation with audio in interactive mode

What is Difference between

difference between FDM and OFDM
Difference between SC-FDMA and OFDM
Difference between SISO and MIMO
Difference between TDD and FDD
Difference between 802.11 standards viz.11-a,11-b,11-g and 11-n
Bluetooth vs zigbee
Fixed wimax vs mobile

RF and Wireless Terminologies

Share this page

Translate this page