Importance

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Abstract

A band gap reference includes an operational amplifier with an output (n23) driving the gate of three current source transistors (501-503). The first current source (501) drives the (+) opamp input (n20) and a transistor (511) functioning as a diode. The second current source (502) drives the (-) opamp input and a series resistor (R.sub.1) and a transistor (512) functioning as a diode. The third current source (503) drives a series resistor (R.sub.2) and diode connected transistor (513). The opamp includes first series transistors (521) and (524) connected between V.sub.DD and V.sub.SS, and second series transistors (522) and (525) connected between V.sub.DD and V.sub.SS. With only two series transistors between V.sub.DD and V.sub.SS at any point, only two times a CMOS transistor threshold drop (less than 1.8 volts) will occur enabling V.sub.DD to range from 1.8-3.6 volts without altering the band gap reference output voltage (V.sub.DIODE). Further, CMOS transistors in the circuit may operate with a 2.7 volt maximum gate to source, or gate to drain voltage.

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First Claim