A 150-V subscriber line interface circuit (SLIC) in a new BiCMOS/DMOS-technology

The presented IC performs the high-voltage functions of an electronic central office subscriber line interface without the need for any transformers or relays. The challenges of subscriber line interface circuit (SLIC) integration stem from the combination of conflicting requirements: low impedance line feeding in a 150-V range, current sensing with 0.2% relative accuracy, and stability up to 200 nF loads, while operating in the harsh environment of the telephone line. The newly developed BiCMOS/DMOS process 170-V smart power technology (SPT 170) together with circuit techniques that strongly emphasize the physical device properties (e.g., buffers with DMOS outputs, n-type supply voltage switch, accuracy by polyresistors) yielded a very robust 30 mm/sup 2/ SLIC. All transmission specifications are met without trimming.