Patent ID: 8294449

Claim:
A bandgap circuit comprising: a bandgap core circuit that includes a first diode having a first junction area and a first forward voltage, a second diode having a second junction area larger than the first junction area and a second forward voltage, a first resistance connected to the second diode; a differential amplifier circuit controlling first and second currents flowing through the first and second diodes respectively, so that the sum of the second forward voltage and a voltage drop of the first resistance approaches the first forward voltage; and a start control circuit that supplies a start signal to the differential amplifier circuit to start up the differential amplifier circuit, the start control circuit discontinuing the supply of the start signal to the differential amplifier circuit after the start control circuit has detected that the differential amplifier circuit has started up, the start control circuit including a replica circuit that replicates an input differential pair of the differential amplifier circuit, a current voltage conversion circuit that detects whether a third current flows through the replica circuit, and a start bias circuit that supplies the start signal to the first diode, wherein after the current voltage conversion circuit has detected that the predetermined current flows through the replica circuit, the start bias circuit discontinues the supply of the start signal to the first diode, wherein the replica circuit has positive and negative inputs that replicate positive and negative inputs of the differential amplifier circuit, the positive input of the replica circuit is connected to the positive input of the differential amplifier circuit and the series connection of the first resistance and the second diode, the negative input of the replica circuit is connected to the negative input of the differential amplifier circuit and the first diode, the start bias circuit supplies the start signal to the negative input of the differential amplifier circuit.