**What You'll Learn?**

# FIR vs IIR Filters

## What is FIR?

FIR stands for Finite Impulse Response. It is a type of digital filter where the output depends only on the input values and a finite number of previous input values.

### Examples of FIR Filters

Examples of FIR filters include low-pass filters, high-pass filters, band-pass filters, and notch filters.

### Uses of FIR Filters

FIR filters are commonly used for audio and image processing, noise reduction, and signal processing applications.

## What is IIR Filters?

IIR stands for Infinite Impulse Response. It is a type of digital filter where the output depends not only on the input values but also on a combination of past input and output values.

### Examples of IIR Filters

Examples of IIR filters include Butterworth filters, Chebyshev filters, elliptic filters, and Bessel filters.

### Uses of IIR Filters

IIR filters are widely used in communication systems, control systems, biomedical signal processing, and many other applications.

## Differences Between FIR and IIR Filters

Difference Area |
FIR Filters |
IIR Filters |
---|---|---|

Filter Type | FIR filters have a finite impulse response. | IIR filters have an infinite impulse response. |

Stability | FIR filters are always stable. | IIR filters can be unstable. |

Phase Response | FIR filters have a linear phase response. | IIR filters can have non-linear phase response. |

Impulse Response | FIR filters have a symmetric impulse response. | IIR filters can have both symmetric and asymmetric impulse responses. |

Design Complexity | FIR filters are relatively easier to design and implement. | IIR filters are relatively more complex to design and implement. |

Filter Order | FIR filters generally have a higher filter order. | IIR filters generally have a lower filter order. |

Frequency Response | FIR filters have a linear phase frequency response. | IIR filters can have non-linear phase frequency response. |

Low-Frequency Roll-off | FIR filters have a better low-frequency roll-off. | IIR filters may have a poor low-frequency roll-off. |

Memory Requirement | FIR filters require more memory due to their longer impulse response. | IIR filters require less memory due to their infinite impulse response. |

Real-Time Processing | FIR filters are more suitable for real-time processing. | IIR filters are generally used for offline processing. |

### Conclusion:

In summary, FIR filters have a finite impulse response, are always stable, have a linear phase response, and are relatively easier to design. However, they require more memory and generally have a higher filter order. On the other hand, IIR filters have an infinite impulse response, can be unstable, have a non-linear phase response, and are relatively more complex to design. They require less memory and generally have a lower filter order. The choice between FIR and IIR filters depends on the specific requirements and constraints of the application.

### People Also Ask:

#### Q: Can FIR filters be unstable?

A: No, FIR filters are always stable.

#### Q: Do IIR filters have a linear phase response?

A: No, IIR filters can have a non-linear phase response.

#### Q: Are FIR filters suitable for real-time processing?

A: Yes, FIR filters are more suitable for real-time processing.

#### Q: What is the main difference between FIR and IIR filters?

A: The main difference is that FIR filters have a finite impulse response, while IIR filters have an infinite impulse response.

#### Q: Which type of filter requires less memory, FIR or IIR?

A: IIR filters require less memory due to their infinite impulse response.