Patent ID: 8217708

Claim:
A temperature sensor, comprising: a temperature-dependent voltage generation circuit for generating a temperature-dependent potential that is dependent on temperature; a current generation transistor that allows a temperature-dependent current to flow through the current generation transistor based on the temperature-dependent potential; a reference current generation circuit for generating a reference current that is independent of temperature; a capacitor that is charged alternately with the temperature-dependent current during a first charge period and that is charged with the reference current during a second charge period; a pulse generation circuit for comparing a charged voltage of the capacitor with a reference voltage to generate a pulse; and a control circuit for alternately supplying the temperature-dependent current and the reference current to the capacitor, the control circuit outputting a temperature-dependent pulse having a time width that is dependent on temperature during the first charge period, and outputting a reference pulse having a time width that is independent of temperature during the second charge period, the temperature-dependent voltage generation circuit comprising: a current source circuit comprising a first metal oxide semiconductor (MOS) transistor and a second MOS transistor; a first bipolar transistor that outputs a first base-emitter voltage varying with temperature, the first bipolar transistor being connected with one of the first MOS transistor and the second MOS transistor as a load of the first bipolar transistor; a second bipolar transistor that outputs a second base-emitter voltage varying with temperature, the second bipolar transistor being connected via a resistor with another one of the first MOS transistor and the second MOS transistor as a load of the second bipolar transistor, the second bipolar transistor being used as a temperature sensor utilizing a band gap of the second bipolar transistor; a first selection switch for switching a connection destination of the first bipolar transistor to one of the first MOS transistor and the second MOS transistor; a second selection switch for switching a connection destination of the second bipolar transistor to another one of the first MOS transistor and the second MOS transistor; and an operational amplifier for amplifying a voltage difference between the first base-emitter voltage and the second base-emitter voltage, wherein the voltage difference varies due to temperature changes, and outputting the temperature-dependent potential determined by amplifying the voltage difference to a gate of the first MOS transistor and a gate of the second MOS transistor from one of an inverting terminal and a non-inverting terminal of the operational amplifier.