Talk:Chebyshev filter

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are chebyshev filters the same as IIS filters?

is the comb filter a sort of chebyshev filter?

does the chebyshev filter work with delayed signal input from its output?

what is the chebyshev filter actually good for? (applications)

--Abdull 17:58, 18 Jun 2005 (UTC)

  1. Never heard of an IIS filter
  2. I highly doubt it. Maybe they are related in some trivial way
  3. All filters delay the signal
  4. They are used anywhere a steep cutoff is required with minimal parts and ripple doesn't matter.  :-) I know they are used in analog to digital converters for one thing. - Omegatron 15:54, July 19, 2005 (UTC)

A chebyshev filter is a modern filter which (like all continuous-time filters)can be implemented as an IIR (infinite impulse response) discrete-time filter. It is based on chebyshev polynomials. Its characteristic in the complex frequency domain is composed of poles lying in the left half-plane and distributed along an ellipse centered at the origin and with zeroes at infinity. The butterworth characteristic can be seen as a special case of the chebyshev since its poles are distributed at uniform angles along a circle. What I would like to know is if the poles of a chebyshev filter are distributed according to some simple rule, for example do vectors from the origin to poles carve out equal segment areas of the ellipse as is the case of the butterworth?

As can be seen from the equation on the article page, the poles can be thought of as uniformly distributed on a circle, and this circle then stretched in each dimension to give an ellipse. Oli Filth 22:35, 10 November 2006 (UTC)

A comb filter is very different from the chebyshev in that its characteristic is composed of finite zeroes, and poles at infinity. It can be implemented as an FIR discrete-time filter.--T. Groover, MSEE


[edit] New LC realization section

Yo I added this section but someone please check for validity. I am not a EE major (I'm in aerospace) but I gleaned the equations off of the 2nd reference on the bottom (which I also added). If someone could check it out for accuracy, etc., that'd be great

Subheight640 15:37, 27 July 2007 (UTC)

[edit] Missing j in Inverse Cheb. Lowpass Zeros?

I think the zeros of the inverse Cheb. should be something like sn = j/cos(Pi/2 * (2*m+1)n), that means imaginary not real. In other words the j is missing. What do You think? I'll change it now. —Preceding unsigned comment added by 213.178.172.228 (talk • contribs) 13:11, 13 September 2007

[edit] Poor Explanation...

There is beauty in the Chebyshev filter but if you read this article you wouldn't know it. I don't have a clue how to manipulate the math graphics, but if I did I could create a much more clear explanation. Basically you want to substitute arcsinh(1/e) with a constant variable, say 'a'. Then you split up the real and imaginary parts of the pole locations into x and y respectively. Then you can show how (x/sinh(a))^2 + (y/cosh(a))^2 = 1. This equation clearly shows that the chebyshev poles are on an ellipse. It can then be compared to the Butterworth filter which has its poles on a circle.