Patent ID: 8138743
Filing Date: 2012-03-20
Classification: G05F

Abstract:
1. A band-gap reference voltage source circuit comprising: a diode-pair circuit including a first diode whose cathode is connected to a ground potential and whose anode is connected to a first voltage detection terminal, a second diode whose junction area differs from a junction area of the first diode and whose cathode is connected to the ground potential, a first resistor which is connected between the first voltage detection terminal and a reference voltage output terminal, a second resistor which is connected between a second voltage detection terminal and the reference voltage output terminal, and a third resistor which is connected between the second voltage detection terminal and an anode of the second diode; a first differential amplifier of an open-drain output type, which is constituted of a first first-conduction-type transistor whose source is connected to a power-supply voltage and whose drain is connected to the reference voltage output terminal, and a first operational amplifier whose noninverting input terminal is connected to the first voltage detection terminal, whose inverting input terminal is connected to the second voltage detection terminal, and whose output terminal is connected to a gate of the first first-conduction-type transistor; and a second differential amplifier of an open-drain output type, which is constituted of a second first-conduction-type transistor whose source is connected to the power-supply voltage and whose drain is connected to the reference voltage output terminal, and a second operational amplifier whose noninverting input terminal is disconnected from each of the first and second voltage detection terminals and is connected to a first bias voltage which is lower than a predetermined voltage at the reference voltage output terminal, whose inverting input terminal is connected to the reference voltage output terminal, and whose output terminal is connected to a gate of the second first-conduction-type transistor.