Patent ID: 8093889

Claim:
A sensor circuit comprising: a sensor element which outputs an output signal that has a first temperature coefficient based on an external factor; an amplifier circuit which amplifies the output signal of the sensor element, and which outputs an output signal that has a second temperature coefficient based on the first temperature coefficient and contains noise; a reference voltage circuit which includes a voltage divider circuit, a first temperature compensating resistor, and a second temperature compensating resistor, and which outputs a reference voltage, the voltage divider circuit including a plurality of resistors that have the same temperature coefficient, the first temperature compensating resistor having a temperature coefficient different from the temperature coefficient of the plurality of resistors, the second temperature compensating resistor having a temperature coefficient different from the temperature coefficient of the plurality of resistors and having a resistance value based on temperature characteristics of the noise, the reference voltage having a third temperature coefficient, which is substantially equal to the second temperature coefficient; and a comparator circuit which compares the output signal of the amplifier circuit and the reference voltage of the reference voltage circuit to output one of a High signal and a Low signal when the output signal of the amplifier circuit is equal to or larger than the reference voltage of the reference voltage circuit, and to output another one of the Low signal and the High signal when the output signal of the amplifier circuit is smaller than the reference voltage of the reference voltage circuit.