Patent ID: 6426669
Filing Date: 2002-07-30
Classification: G05F

Abstract:
A low voltage bandgap reference circuit comprisinga first bipolar NPN transistor having a collector current I and having its emitter coupled to a bias voltage supply via a first resistor; a second bipolar NPN transistor having the collector current I and having its emitter coupled to the bias voltage supply via a second resistor, the base of the first NPN transistor being connected to the base of the second transistor, the emitter of the second NPN transistor having an area that is greater than the area of the emitter of the first NPN transistor; an inverting amplifier connected between the collector of the second NPN transistor and an output node Vout of the bandgap reference circuit; a third resistor connected between the base of the first NPN transistor and the emitter of the first NPN transistor; a fourth resistor connected between the output node Vout and the emitter of the second NPN transistor, wherein the second, third and fourth resistors satisfy the condition R2=R3&CenterDot;R4R3+R4;andan amplifier connected between the collector of the first NPN transistor and the commonly-connected bases of the first and second NPN transistors, whereby the amplifier sets the collector current of the first NPN transistor equal to I.