NetConf: a single chip PCM conference circuit with automatic gain control, attenuation, noise suppression, soft reset and multiple frame synchronization timing

This paper presents a unique 2-stage pipeline PCM conference architecture, called NetConf, specially designed and realized as a single chip VLSI for processing PCM channels in order to provide conference in digital switching systems. The NetConf conference circuit overcomes the manual handling of overflow problem, that exist in the current architectures, with a unique 2-stage pipelined architecture and a new AGC algorithm. The circuit can also provide regular connection and capable of doing 3 Level attenuation, 4 level noise suppression on all or any selected channel. The circuit can be soft reset and accept different frame synchronization timings. The conference circuit realized by European Silicon Structures´ 0.7 micron CMOS technology and packaged in a 24 pin plastic DIL package. The die is 12 mm² and consists of 12,000 gates including two four-ports static RAMs. This newly proposed 2-stage pipeline conference architecture provides better overflow and noise performance over existing architectures