A single chip modem

The authors describe a VLSI CMOS chip designed to be used as a core processor in a high-speed modem (14400 b/s). This VLSI circuit integrated a 16-b fixed-point digital signal processor with its associated data and instruction memories, an analog-digital and digital-analog front-end converter using sigma-delta modulation, and a function called modem adaptor handling the signal-processor clocks and interrupts, the data transfers between the sigma-delta and the processor, and the communications between the single-chip modem (SCM) and slow external input-output devices. The SCM is designed in a submicron CMOS technology. The logic is implemented using a mixed library of standard-cell and gate-array books