Patent ID: 7592859

Claim:
A circuit to compare an input signal with a threshold level, the circuit comprising: a Widlar bandgap circuit including: a first resistor that receives the input signal; a first bipolar transistor that is diode-connect and that is coupled to the first resistor at its collector; a second resistor that receives the input signal; a second bipolar transistor that is coupled to the base of the first transistor at its base and that is coupled to the second resistor at its collector; a third resistor that is coupled to the second transistor at its emitter; an intermediate stage coupled with the output of the Widlar bandgap circuit, wherein the intermediate stage includes: a fourth resistor that receives the input signal a third bipolar transistor that is coupled to the fourth resistor at its collector and that is coupled to the collector of the second bipolar transistor at its base; a final stage coupled with the output of the intermediate stage, the final stage to provide an output based on the input signal and the threshold level; a fifth resistor that is coupled between the collector of the first bipolar transistor and the ground potential; a sixth resistor that is coupled between the that is coupled between the collector of the second bipolar transistor and the ground potential, wherein the ratio of the first resistor to the fifth resistor is approximately equal to the ratio of the second resistor to the sixth resistor.