A High Voltage Line Driver for Subscriber Loop Interfaces in a Low Voltage Submicron BiCMOS Technology

This paper presents a 30 V line driver for short loop subscriber line interface circuit applications. The high voltage line drivers was implemented in a low-voltage 0.8 μm BiCMOS process using 30 V extended-drain MOS transistors, fully compatible with the low voltage technology. Using a Quasi-Current Mirror architecture for the output stage, the line driver is capable of delivering more than 30 mA current into the lines with an idle current as low as 1 mA, satisfying the short loop requirements. With less than 0.24 mm2 area, the circuit can be easily integrated with low-voltage circuitry on a single chip.