A CMOS Programmable Anticlipping Circuit for Digital Telephones

An on-chip CMOS digital anticlipping circuit that requires no external components is presented. Four anticlipping thresholds, i.e. ¿15dBmO, ¿13dBmO, ¿9dBmO, and ¿7dBmO, and four gain recovery time constants, i.e. 16msec, 32msec, 128msec, and 256msec, can be programmed via a dedicated 4-bits control register. The extra area added to the chip to implement the anticlipping function is about 1 mm² in a 1.5¿ single-poly double-metal N-well CMOS technology. The circuit can be powered with a single supply ranging from 5V down to 2.7V.