Howtosignalprocessing
- What is the significance of poles and zeros in filters?
- What is the purpose of increasing the number of poles in a filter?
- What is the advantage of designing IIR filters using pole zero plots?
- How do you identify a filter from pole zero plot?
What is the significance of poles and zeros in filters?
Every digital filter can be specified by its poles and zeros (together with a gain factor). Poles and zeros give useful insights into a filter's response, and can be used as the basis for digital filter design.
What is the purpose of increasing the number of poles in a filter?
In simple terms the more the poles the more the attenuation for a given frequency. In the chart above you can see that at 2.0 times the corner frequency the attenuation for a 2 pole filter will be about 12 db, for a 4 pole it will be about 24 dB, a 6 pole will be about 36 dB, etc.
What is the advantage of designing IIR filters using pole zero plots?
This is useful for illustrating how the filter causes impulsive inputs to spread out in the time domain. The magnitude and phase plots show and , respectively, plotted with so that the frequency ranges from up to , which are the minimum and maximum frequencies representable in a digital system.
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!
