Patent ID: 8063676

Claim:
A band-gap reference voltage detection circuit comprising: a first current source (I 1 ); a second current source (I 2 ); a first bipolar junction transistor (Q 1 ) having a collector connected to the first current source (I 1 ), a base, and an emitter; a second bipolar junction transistor (Q 2 ) having a collector connected to the second current source (I 2 ), a base connected to the base of the first bipolar junction transistor (Q 1 ), and an emitter; a first resistance (R 1 ) connected between the emitters of the first (Q 1 ) and second bipolar junction transistors (Q 2 ); a second resistance (R 2 ) connected between the emitter of the first bipolar junction transistor (Q 1 ) and a ground reference potential; and an operational amplifier (A 1 ) having a non-inverting input (+) connected to the collector of the first bipolar junction transistor (Q 1 ), an inverting input (−) connected to the collector of the second bipolar junction transistor (Q 2 ), and an output, wherein the base-emitter area of the second bipolar junction transistor (Q 2 ) is N times larger than the base-emitter area of the first bipolar junction transistor (Q 1 ), the transistor bases are configured to receive an input voltage, and the operational amplifier (A 1 ) output is the band-gap reference voltage detection circuit output, wherein the first current source (I 1 ) and the second current source each are composed of a bias resistance (Rbias) connected to a voltage source, and wherein the first, second and bias resistances are active-based resistors sized to have intrinsic RC time constants faster than voltage source ramp rates.