Pole zero plot of filter

1. What is pole zero in filter design?
2. How do you identify a filter from pole zero plot?
3. What is the relation between poles and zeros of all pass filter?

What is pole zero in filter design?

Poles and zeros are properties of the transfer function, and in general, solutions that make the function tend to zero are called, well, zeros, and the roots that make the function tend towards its maximum function are called poles.

How do you identify a filter from pole zero plot?

Well if the pole is more closer to the origin, i.e, if it's pole dominant then the system is LPF. Similarly, if it's zero dominant it's a HPF. low pass filters will be pole dominant whereas HPFs will be zero dominant and all pass filters will have a symmetrical arrangement of poles and zeroes!

What is the relation between poles and zeros of all pass filter?

In summary, a single-pole, single-zero all-pass filter passes all frequency components with constant gain and a phase shift which may be adjusted by the placement of a pole. Taking Z₀ near the unit circle causes most of the phase shift to be concentrated near the frequency where the pole is located.