Infinite impulse response filter 2nd,3rd order high pass Matched Z approximation.

Cuthbert Nyack
The sampled "equivalent" of a second and third order Butterworth high pass filter derived by use of the Matched Z approximation is shown in the applets below. The Butterworth filter has an lower 3dB frequency of 1rad/s. First applet shows a second order filter and the second shows a third order filter. In applet below vertical scale is from 0 to 4/3 for amplitude, -pi to pi/3 for phase and horizontal scale is from 0 to 4rad/s.

In both applets red shows the sampled filter response, orange shows the analog filter response, green shows the sampled filter phase and cyan shows the analog filter phase.

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COPYRIGHT © 1999 Cuthbert A. Nyack.