Custom design of a VLSI PCM-FDM transmultiplexer from system specifications to circuit layout using a computer-aided design system

The computer-aided design of a VLSI PCM-FDM transmultiplexer is presented. The entire design process from system specifications to integrated circuit layout is carried out with the aid of specialized computer programs for analysis, synthesis and optimization at each design level: the filter network, the architecture and the circuit layout. These CAD tools support a top-down custom design methodology based on bit-serial architectures and standard cells. A customized architecture is constructed, which is integrated using a 5- m CMOS cell library. The results are compared with a fully manual design and demonstrate the power of architecture based computer-aided design methodologies for VLSI filtering. By combining both synthesis as well as optimization aids at each design level, it is possible to achieve a high degree of automation while retaining an efficient use of silicon area, high throughput and moderate power consumption.