The CXD2724AQ-3 is a CMOS LSI developed for Dolby Pro Logic Surround. A SRAM for short delay and AD/DA converters are built in, and all functions necessary for Dolby Pro Logic Surround such as an adaptive matrix, a passive decoder including BNR, auto input balance, a noise sequencer and center channel mode control are contained on a single chip. Further, this LSI also supports Dolby 3 Stereo and Virtual Dolby Surround.