Analog signal processor IC´s for sound field effects

Two integrated circuits (ICs), developed for use with the Sound Field System developed by Dolby Laboratories, are described. This system provides TVs and video cassette recorders (VCRs) with sound localization effects similar to those used in movie theaters. The first IC is an active decoder that consists of three subelements: on adaptive matrix for direction enhancement, a center-mode control to select functions of the center speaker, and a passive decoder that uses a fixed matrix instead of the adaptive matrix and in which the function for the center speaker is not as versatile as for the active decoder. A separate passive decoder IC was fabricated using bipolar CMOS technology. Using these ICs cuts the size of the Dolby Sound Field System by over 60%, allowing the addition of the system as part of the built-in TV and VCR circuitry.