8. IIR Filters - Infinite Impulse Response - Digital Filter Basics

In this video, we'll subject an impulse signal through a first order feedback filter to get an impulse response, and we'll see why this response is called an infinite impulse response and what makes a filter unstable. We'll then briefly talk about the zeros and poles of a filter, and make a simple modification to create a p-z filter. We'll end the discussion with the advantages and disadvantages on an IIR filter.

Content:
0:00 Impulse response
4:42 Poles and zeroes
8:41 p-z filter
9:27 Direct form 1 and 2
10:23 Bi-quads / Advantages
13:02 Disadvantages

Repository:

References:
Designing Audio Effect Plugins in C++, Will C. Pirkle -
Digital Filters: A Practical guide, David Dorran

In this series on Digital Filter Basics, we'll take a slow and cemented dive into the fascinating world of digital filter theory. Many resources present this topic with dense and exhausting mathematics. Although a fair understanding of complex mathematics is required to fully comprehend the science of filter design, understanding the basics of filters and how they fundamentally work is better left to analysis and visualizations, which I try to do in this series. We'll learn about feedforward and feedback filter topologies, impulse and impulse responses and and wide variety of other topics.

If you've got any questions, suggestions or recommendations, type them out here, or send me a message on any of my social channels mentioned below.

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[baptistelegoff]

Finally a comprehensive and visual way to understand these concepts. Thanks !

[HimanshuAtchutha]

great work! I finally understood what an IIR is

[itryforwhat]

This one really helps me a lot to understand IIR filter. Very glad if you can make a video about adaptive filter.

[jayhu]

Another amazing video from Akash senpai 🤩

[hrushik]

Thank you so much for such a clear explanation

[tillgo]

So good man thank you these videos, should be on the ytube front page

[ArsalanAhmadi-cx]

Very informative video. Thank you very much!

[Alexagrigorieff]

Fun fact:
Although it's very well known that an IIR cannot have a constant group delay (linear phase response), you *can* have a constant (very close) group delay by applying an IIR to a *time-limited* signal in forward direction, making sure to keep filtering until the tail decays enough, and then in *backward* direction.

[guillaume]

Hi. Thanks for this neat video.
I am not sure that phase is not perceived by human ears... what I read in the past is that phase of an audio wave is synonym of distance. If you change the phase, you may change the 3D effect of the audio. If so, it would be even more perceptible if you have stereo... for example, the exact same wave (I mean, same frequency), but with difference of phase. You may feel your left ear is closer to the emitter than your right ear, or the other way round.
Another approach that includes phase is group delay and phase delay.
As said earlier, I do not master digital filters but I have way more experience in analog electronics and automation. I don't know much about digital filters as I only studied their theory at school but never have gotten the opportunity to run some practice around them.

[elsharko]

This is amazing! Thank you! I like and I subscribe

[williamogilvie]

This guy needs to find a new career. EE and digital signal processing is not something he understands.. just dumb babble talk. Anyone is better spending their time reading Oppenheimer's book.