Integration of a short-loop SLIC in a low-voltage submicron BiCMOS technology

Abstract

This paper presents the high-voltage building blocks of a short-loop subscriber line interface circuit (SLIC), implemented in a 5 V 0.8 /spl mu/m BiCMOS technology using fully compatible high-voltage MOS transistors. The presented circuits include a 30 V class-AB line driver, a 30 V fully differential preamplifier, and a novel common-mode feedback circuit. Using a floating-current-mirror technique, the line driver features a well-controlled quiescent current of 600 /spl mu/A and is capable of delivering more than 30 mA of current into the loop. With an area of 0.34 mm/sup 2/, the line driver exhibits a bandwidth of 3.6 MHz for a 600 /spl Omega//1 nF load. The preamplifier and its common-mode feedback circuit feature a compact size (0.1 mm/sup 2/) and small power dissipation (10 mW). The circuits are ideal for the integration of a short-loop SLIC on a single chip with other low-voltage building blocks.