Infinite impulse response filter 2nd order lowpass
Matched Z approximation.
The applet below shows the impulse response of a 2nd order Butterworth
filter in red and the impulse response of a
sampled version of the filter in magenta
obtained by using the Match Z approximation. The 2 responses are
"identical" for small sampling times but some differences develop as the
sampling time is increased.
Applet below is similar to the one above but the zeros at infinity
were not matched when calculating the sampled Transfer Function. In both applets
the horizontal scale is from 0 to 10s and the vertical is from -1 to +1 when gains are 1.
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COPYRIGHT © 1999 Cuthbert A. Nyack.