Explain the difference between FIR filter and IIR filter in detail

Digital filters are widely used in hardware circuit design , Generally divided into FIR Filter and IIR filter . Now let's talk about the specific differences

One 、FIR filter

Definition :

FIR The filter is a finite length unit impulse response filter , It is also called non recursive filter , It is the most basic component in digital signal processing system , It can guarantee arbitrary amplitude frequency characteristics and strict linear phase frequency characteristics , At the same time, the unit sampling response is finite , So the filter is a stable system .

characteristic :

• FIR The main feature of the filter is that there is no feedback loop , Strong stability , Therefore, there is no problem of instability ;

• FIR It has strict linear phase , The amplitude characteristic can be set at will , Ensure accurate linear phase ;

• FIR The design method is linear , Hardware is easy to implement ;

• FIR relative IIR For filters , At the same performance index , Higher order , Yes CPU The performance should be higher .

Two 、IIR filter

Definition :

IIR The filter is an infinite impulse response filter , Also known as recursive filter , That is, the structure has a feedback loop .

characteristic :

• IIR The system function of digital filter can be written in the form of closed function , With feedback loop ;

• IIR Phase nonlinearity of digital filter , The phase characteristic is difficult to control , Varies with the cut-off frequency , When the phase requirement is high , Need to add phase calibration network ;

• IIR The filter has a history of output feedback , Same as FIR Better filtering effect than that at the same order ;

• IIR Digital filter