Differenece between FIR and IIR Filter.

FIR vs IIR filter:

FIR Filter	IIR Filter
A finite impulse response (FIR) filter produces an output that will go to zero when the input goes to zero and stays zero	An infinite impulse response (IIR) filter produces an output that may continue indefinitely even after its input goes to zero and stays zero.
Its response to an impulse function input is finite	Its response to an impulse function input is infinite
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 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)
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 have no analog equivalent	IIR filters have analog equivalent
FIR filters are used as anti-aliasing, low pass and baseband filters	IIR filters are used as notch (band stop), band pass functions
Transfer function of FIR filter will have only zeros, need more memory	Transfer function of IIR filter will have both zeros and poles and will require less memory than FIR counterpart.
An FIR filter’s z-Transform has zeroes and poles only at 0 + j0, so it is always stable	An IIR filter’s z-Transform has pole(s) and may also have zeroes, so it may be unstable if any of the poles are outside the unit circle
FIR Filters have linear phase.	IIR filters don’t have linear phase so they are used at places where phase distortion is tolerable.

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.