A single-chip V.32 bis modem

High-speed modems have so far been constructed with several functional chips. One typical example is the front-end processor chip (FEP) incorporating the ADC, DAC and necessary arithmetic circuitry, combined with an external digital signal processor (DSP) chip. That single-chip high-performance V.32 bis modem incorporates closely-interacting FEP and DSP sections, resulting in cost and space savings in personal communication equipment. The modem described here is composed of an embedded DSP, a ROM and RAM for storing the programs and data, and a high-precision oversampling sigma-delta ADC/DAC. The chip performs 9 data modem and 4 fax modem standard modes. The diagram is divided into four major sections: a DSP block, a memory (MEM) block, an ADC/ DAC block, and a serial data-processing (SDP) block. The DSP block performs modulation, demodulation, echo cancelling (EC), Viterbi decoding (VTB), channel filtering (CF), and automatic gain control.<>