Accurate Current Sensing

摘要

A current sense circuit for a pass transistor is described. The circuit comprises a sense transistor having input and control ports that are coupled to input and control ports respectively of the pass transistor. The circuit comprises a differential amplifier comprising a differential input and output. An output port of the pass transistor is coupled to a first port of the differential input and an output port of the sense transistor is coupled to a second port of the differential input. The differential amplifier comprises a first sub-amplifier and a second sub-amplifier that are arranged in parallel and which are operated in an auto-zero phase and in an amplification phase in an alternating manner, and which are operated in the auto-zero phase in a mutually exclusive manner. The output of the differential amplifier is used to control voltage drops across the sense transistor and the pass transistor.

主权项

1) A current sense circuit for a pass transistor, wherein the current sense circuit comprises,
a sense transistor having an input port that is coupled to an input port of the pass transistor and having a control port that is coupled to a control port of the pass transistor; and a differential amplifier comprising a differential input and an output; wherein an output port of the pass transistor is coupled to a first port of the differential input and wherein an output port of the sense transistor is coupled to a second port of the differential input; wherein the differential amplifier comprises a first sub-amplifier and a second sub-amplifier that are arranged in parallel and which are operated in an auto-zero phase and in an amplification phase in an alternating manner, and which are operated in the auto-zero phase in a mutually exclusive manner; wherein the output of the differential amplifier is used to control a voltage drop across the sense transistor and the pass transistor.