An analog front end for high speed fast turnaround modems

A single-chip analog front end (AFE) for V.32 9600-b/s fast turnaround modems is presented. The AFE mixes analog and digital circuits to achieve a high level of integration of modem front end functions. The AFE integrates 80 poles of switched-capacitor filters for all transmission modes with DSP (digital signal processor) and microprocessor interfaces, 8-bit linear A/D (analog-to-digital) and D/A (digital-to-analog) converters, a channel compromise equalizer, and various other modem front-end functions. The AFE maintains a worst-case 40 dB SNR (signal-to-noise ratio) over a received signal dynamic range of 45 dB. The chip dissipates 300 mW with ±5-V supplies, and occupies 63000 mil² in a 3-μm double-poly CMOS process