## What is maximally flat response filter?

The Butterworth filter is a type of signal processing filter designed to have a frequency response that is as flat as possible in the passband. It is also referred to as a maximally flat magnitude filter.

### Why is it called Butterworth filter?

Hence the Butterworth filter is also known as “maximally flat magnitude filter”. It was invented in 1930 by the British engineer and physicist Stephen Butterworth in his paper titled “On the Theory of Filter Amplifiers”.

**What is Epsilon in Butterworth filter?**

The frequency response of the nth order Butterworth filter is given as. Where ‘n’ indicates the filter order, ‘ω’ = 2πƒ, Epsilon ε is maximum pass band gain, (Amax). If we define Amax at cut-off frequency -3dB corner point (ƒc), then ε will be equal to one and thus ε2 will also be equal to one.

**What is flat flat filter?**

Explanation: The key characteristic of the butterworth filter is that it has a flat pass band as well as stop band. So, it is sometimes called a flat-flat filter.

## Why Butterworth response called a maximally flat response?

Butterworth filters are called maximally flat filters because, for a given order, they have the sharpest roll-off possible without inducing peaking in the Bode plot. The two-pole filter with a damping ratio of 0.707 is the second-order Butterworth filter.

### What is stopband bandwidth?

A stopband is a band of frequencies, between specified limits, through which a circuit, such as a filter or telephone circuit, does not allow signals to pass, or the attenuation is above the required stopband attenuation level.

**What is pole in filter?**

The term in filters comes from ‘pole’ as a term in mathematics, it’s a type of singularity where the function goes to infinity. When analyzing how an alaog filter affects the sound, that response surface can have many different numbers of poles, in the mathematical sense.

**Which analog filter approximation is called maximally flat?**

Butterworth filters

Butterworth filters are called maximally flat filters because, for a given order, they have the sharpest roll-off possible without inducing peaking in the Bode plot.