Patent ID: 8102193

Claim:
An apparatus comprising: a power transistor; a sensing transistor configured to copy a current flowing through the power transistor at a predetermined ratio; a current sensing resistor configured to detect a sensing voltage from the current copied by the sensing transistor; a first input resistor configured to convert an input voltage to a first current, the first input resistor having a first end connected to an end of the current sensing resistor; a second input resistor configured to convert the sensing voltage to a second current, the second input resistor having a first end connected to another end of the current sensing resistor; a cross self-biasing cascode block configured to equally adjust the first and second currents at each end of the first and second input resistors; a common gate transistor and a reference resistor configured to convert a current output of the first and second input resistors to a final sense voltage; and a current source for each end of the first and second input resistors.