What is the difference between IIR and FIR Filters?

The number one difference between IIR or Infinite IR and FIR or Finite IR filters is that they are used in different applications. For instance, FIR filters are used for applications that exhibit linear characteristics. On the contrary, IIR filters are independent of the linear-phase characteristics, meaning you can use them in non-linear applications. One of the downsides of FIR filters is that they require more memory. IIR, on the other hand, requires less memory because it consists of poles and zeros. FIR filters are easy to implement because of their delay characteristics. In contrast, IIR filters can be difficult to use because they are usually unstable, but FIR filters are more stable. Unlike IIR filters that use o/p and I/p, FIR filters use only I/p. While IIR filters are used to tap lower-orders, FIR filters are effective for higher orders. Unlike the IIR that can produce analog filter response, FIR cannot.

There are two things that you need to look out for when you are trying to find the differences between FIR and IIR. The first thing is the impulse response. You can expect that the IIR filter will have a long impulse response especially when you compare it to the FIR filter with a response time that is as long as the tap count. The second thing to remember is the pulse. The pulse is always going to be more delayed for the FIR as compared to the IIR. These two classes of digital filters are often compared with each other. IIR filters are sometimes considered to be better simply because they would require fewer coefficients as compared to FIR especially when doing different filtering operations.

The two filters that are often compared to each other are IIR and FIR. IIR is known to have no particular phase, while the FIR is known to be something that can be used in a more stable manner. There are a lot of people who prefer the FIR because this is more stable, and there is no need to worry about feedback, which is usually one of the main issues that you can expect when you use IIR.

The only time when you are recommended to use the IIR is when you would need to have an alternate. For example, the use of the FIR is already too long and would need an alternative. The IIR can be useful for sure.

IIR filters are very difficult to operate and control, which denotes they are non-user friendly interface. They do not have a particular phase, while FIR filters can always make a linear phase possible. IIR is not stable, while FIR is very stable. The cycle of FIR is not limited, while IIR has limited cycles.

FIR filters help in the achievement of fractional constant delay. FIR does not have any analog history, while IIR is actually derived from analog. IIR filters can make the implementation of polyphase possible while FIR can be made casual. IIR filters need more #MAD than FIR filters.

The reason is that the order of FIR is higher when compared to IIR filters. The IIR filters are of low orders, and they use polyphase structures. #MAD is a criterion that is used to compare the IIR filter and FIR filter. It represents a number of multiplications together with addition.