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

A 5-V CMOS line controller is presented. The circuit was designed using a 2-μm CMOS technology with two layers of polysilicon and two layers of metal. The total circuit area is 15 mm², of which 6.5 mm² is used for converters, 1.6 mm² for the DC feed controller, and 1.5 mm² for the digital interface; the rest is overhead for periphery. Audio converter performances, such as 16-b dynamic range or 15-b A/D linearity, and their stability over process and operating condition variations point out the efficiency and robustness of the selected design techniques. These are a tone-tolerant second-order delta-sigma modulator design, a matching-independent 2-b D/A conversion scheme, a clock-feedthrough compensation technique, and a two-stage amplifier with a noise bandwidth limited by the switches. Converter performances and DC feed controller absolute accuracy and programmability match the new line card design targets and indicate that this circuit is viable for large volume production