Patent ID: 6735302
Filing Date: 2004-05-11
Classification: H03F,H04L,H04M

Abstract:
A telephony line interface circuit comprising a SLIC including an operational amplifier having a composite differential MOSFET-bipolar driver stage, each side of the driver stage including:a MOSFET output driver; at least one first bipolar transistor coupled to the MOSFET output driver; a feedback path coupled between the first bipolar transistor and an output of the MOSFET; and a diode-connected second bipolar transistor coupled to a base of the first bipolar transistor, the diode-connected second bipolar transistor biasing the first bipolar transistor, wherein the first bipolar transistor biases the MOSFET to output a current, the feedback path provides an indication of the current from the MOSFET to the first bipolar transistor, and the first bipolar transistor adjusts the bias in response to the indication.