Swithced-Capacitor Stereo Decoders for T.V. and Radio Receivers

Conventional stereo decoder i.c.\´s require many off-chip components and several adjustments. This paper describes two stereo-decoder i.c.\´s, which use switched-capacitor techniques to allow full integration and elimination of adjustments. The first decoder is a decoder for television receivers which are based on the so-called "two-carrier" system (1). A second sound carrier is used here, that contains stereo information in the case of "stereo-mode", or information which is independent of that in the first channel, for instance a second languaoe, in the case of "dual mode". The second decoder is an fm-stereo-multiplex decoder for f.m.-radio receivers, which decodes a multiplex signal into a "left" and a "right" signal. A new system approach not only resulted here in full integration, but also in an improved specification. This approach can also be used for stereo decoders for t.v. receivers which are based upon a multiplex system, like for instance the recommended system in America (2).