Patent ID: 7495505

Claim:
A low supply voltage band-gap reference circuit, comprising: a positive temperature coefficient current generation unit, for generating a positive coefficient current according to a first internal voltage and a second internal voltage, the positive temperature coefficient current generation unit comprising: a first operational amplifier, having a positive input end and a negative input end for respectively receiving the second internal voltage and the first internal voltage and outputting a bias voltage; and a fourth transistor, having a base and a first emitter/collector coupled to a first constant voltage, and a second emitter/collector for providing the first internal voltage; and a negative temperature coefficient current generation unit, comprising: a voltage-to-current converter, for generating a corresponding first current according to the first internal voltage of the positive temperature coefficient current generation unit, the voltage-to-current converter comprising: an eighth transistor, having a first source/drain, a second source/drain, and a gate; and a second operational amplifier, having a positive input end coupled to the second emitter/collector of the fourth transistor, a negative input end coupled to the first source/drain of the eighth transistor, and an output end coupled to the gate of the eighth transistor; and a current mirror, having a master current end coupled to the voltage-to-current converter, for receiving the first current, duplicating the first current according to a predetermined proportion, and providing a negative coefficient current at a slave current end of the current mirror, wherein the sum of the positive coefficient current and the negative coefficient current is the output of the band-gap reference circuit.