A 5-V CMOS line controller with 16-bit audio converters

A 5-V CMOS line controller including 96-dB D/A and 100-dB A/D converters is described. A DC-feed controller synthesizes adjustable line characteristics. The audio converter performances, such as 16-b dynamic range or 15-b A/D linearity, and their stability with respect to process and operating condition variations demonstrate the efficiency and the robustness of the selected design techniques. These are a tone-tolerant second-order delta-sigma modulator design, a 2-b D/A conversion scheme, a clock-feedthrough compensation technique, and a two-stage amplifier with noise bandwidth limitation in the switches. Converter performances, DC-feed controller absolute accuracy, and programmability match new line card design targets and indicate that this circuit is viable for large volume production