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Engineering Brief

Capacitor Distortion in High-Order Active Filters

Authors: Self, Douglas

AES Convention 144 · Paper 422 · May 2018

Abstract

Some non-electrolytic capacitor types such as polyester generate distortion when they have a significant signal voltage across them. This can be avoided by using polypropylene or polystyrene types but they are larger and more expensive. I have previously shown that in 2nd-order Sallen & Key filters, both lowpass and highpass, only one of the two capacitors has to be of the expensive sort to obtain the same freedom of distortion achieved with two. The Geffe configuration allows 3rd and 4th-order filters to be realized economically in one stage, and it is shown that here too only one linear capacitor is required in both lowpass and highpass cases, saving a lot of money.

Details

Published in
AES Convention 144
AES Convention
144
Paper number
422
Publication date
May 6, 2018
Session subject
Signal Processing/Audio Effects & Instrumentation/Measurements/Forensics
Affiliation
The Signal Transfer Company, London, UK (See document for exact affiliation information.)
Type
Engineering Brief