Patent ID: 7501853
Filing Date: 2009-03-10
Classification: H03K

Abstract:
1. A semiconductor device comprising: a first circuit for generating a constant current on the basis of a reference voltage corresponding to a ground potential point of the circuit; a first resistive element whose one end is connected to a power supply voltage terminal, and to which the constant current generated by the first circuit is passed; a first differential amplifier having two input terminals to one of which a voltage generated by the first resistive element is supplied; a first MOSFET of a first conduction type whose source is connected to the power supply voltage terminal, and whose gate receives an output voltage of the first differential amplifier, the first MOSFET feeding back a drain voltage to the other input terminal of the first differential amplifier; a first current source provided between the drain of the first MOSFET and the ground potential point of the circuit, and setting a current to be passed to the first MOSFET; and a second MOSFET of the first conduction type whose source is connected to the power supply voltage terminal, and whose gate and the gate of the first MOSFET are commonly connected, wherein the second MOSFET is used as a resistive element whose resistance value is set in correspondence with the reference voltage and current of the first current source, wherein a positive power supply voltage is supplied to the power supply voltage terminal, wherein the first and second MOSFETs are P-channel MOSFETs, wherein the first circuit comprises a second differential amplifier, third and fourth P-channel-type MOSFETs, fifth and sixth N-channel-type MOSFETs, and a second resistive element, wherein the reference voltage is supplied to one of two input terminals of the second differential amplifier, wherein the sources of the third and fourth MOSFETs are connected to the power supply voltage terminal, wherein the sources of the fifth and sixth MOSFETs are connected to the ground potential point of the circuit, wherein the second resistive element is connected between the drain of the third MOSFET and the ground potential point of the circuit, wherein the other input terminal of the second differential amplifier is connected to the drain of the third MOSFET, wherein the gate and source of the fourth MOSFET are connected to the gate and source of the third MOSFET, respectively, wherein the gate and the drain of the fifth MOSFET are connected to each other, wherein the sixth MOSFET is connected to the fifth MOSFET so as to form a current mirror circuit, wherein the drain current of the fourth MOSFET is supplied to the drain of the fifth MOSFET, and wherein the drain current of the sixth MOSFET is used as the constant current.