Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uakari.primate.wisc.edu!ginosko!gem.mps.ohio-state.edu!tut.cis.ohio-state.edu!ucsd!anise.acc.com!ivucsb!todd From: todd@ivucsb.sba.ca.us (Todd Day) Newsgroups: comp.dsp Subject: Designing the analog filter adendum Message-ID: <1989Sep27.030845.2927@ivucsb.sba.ca.us> Date: 27 Sep 89 03:08:45 GMT Reply-To: todd@ivucsb.sba.ca.us (Todd Day) Organization: Disillusioned Graduate Hackers, Santa Barbara, CA Lines: 16 I forgot to mention what analog filter I chose and why. I chose Chebychev because it has no ripple in the passband and takes half as many poles as the Butterworth. Each complex pole pair can be done with one op-amp, so the fewer pairs, the better. However, we do have a phase problem. My Chebychev design has a phase lag of 180 degrees at 20kHz. The phase starts taking off at about 2kHz. This is no big deal for me, as I am dealing with yucky movie and TV signals, but for those hi-fi nuts who buy expensive cable and interconnects, this is bloody murder... -- Todd Day | todd@ivucsb.sba.ca.us | ivucsb!todd@anise.acc.com "Ya know, some day these scientists are going to invent something that can outsmart a rabbit" -- Bugs Bunny