An octal channel signal processor for subscriber line interface

This paper describes the design and measurement results of an octal mixed analog-digital signal processor used for the Alcatel subscriber line circuit. The device includes 8 analog front ends serving 8 subscriber line terminals and DSP functions such as decimation, interpolation and digital sigma-delta modulation which are included as independent datapaths. The D/A conversion of the 12/16 kHz metering signal is also integrated on the circuit. The chip is processed in a 0.7 ¿m CMOS technology on a 52 mm² die area, consumes 300 mW from a single 5V power supply (all lines operational). The digital interface is 3.3 V compatible.