The TP3094 is a monolithic PCM Codec and Filter device implemented using a digital signal processing architecture. It provides four voice channels, combining transmit bandpass and receive low pass channel filters with companding A-law or m-law PCM encoders and decoders. The device is fabricated using National’s advanced CMOS process. The device includes anti-aliasing filters and sigma-delta converters dedicated to each channel, and by a common signal processing unit which performs all the remaining filtering and processing for the four channels. The TP3094 includes a flexible PCM digital interface, which allows the device to be connected to PCM busses of different formats. It can also be connected with other TP3094 devices in a cascade fashion, for a system with up to 128 POTS interfaces (when a 2.048MHz PCM bus is used).