A monolithic 70-V subscriber line interface circuit

The design of a new monolithic 70-V BIMOS line interface circuit (BLIC), developed as a direct interface to the subscriber line, is described. This is the basic analog segment of a new subscriber-line interface circuit (SLIC). The LSI chip has been designed using a 70-V BIMOS process, combining high- and low-voltage bipolar transistors (70 and 15 V) with CMOS (15-V) transistors all using the same junction depths. The LSI chip meets stringent requirements on several specifications and performs ten basic functions.