Patent ID: 6765431
Filing Date: 2004-07-20
Classification: G05F

Abstract:
A reference having a bandgap reference output and a bandgap reference ground connection comprising:first, second, third and fourth transistors, each having an emitter, a base and a collector; the first and second transistors each being diode connected; the third and fourth transistors having a common emitter connection; a resistor in series with the second transistor; the first transistor and the series combination of the second transistor and the resistor each being resistively biased between the bandgap reference output and the bandgap reference ground connection in relation to the relative sizes of the first and second transistors to operate the first transistor at a higher current density than the second transistor; the bases of the fourth and third transistors being coupled to be responsive to the difference in voltage across the first transistor and the series combination of the second transistor and the resistor, respectively, the third and fourth transistors each being resistively biased in relation to the relative sizes of the third and fourth transistors to operate the third transistor at a higher current density than the fourth transistor; the resistor and the first, second, third and fourth transistors being coupled to define a closed loop comprising the resistor, the difference in the base emitter voltages of the first and second transistors and the difference in the base emitter voltages of the third and fourth transistors; and, an amplifier having a differential input responsive to the difference in the voltages across the resistive biasing of the third and fourth transistors, and an output coupled to the bandgap reference output.