Patent ID: 7498865

Claim:
A semiconductor integrated circuit, comprising: a main circuit including a plurality of MOS transistors in which a source potential and a substrate potential are separated from each other, and operating while receiving an operating power supply voltage; and a substrate potential control circuit for controlling the substrate potential of a MOS transistor in the main circuit so that a saturation current value of the MOS transistor is equal to a target saturation current value, the substrate potential control circuit, including: a constant current generation circuit; a current-voltage conversion circuit including a MOS transistor provided therein and having current-voltage conversion characteristics that change according to the substrate potential of the MOS transistor provided therein for converting a constant current value of the constant current generation circuit to a voltage value; and a differential amplifier circuit comparing the voltage value generated by the current-voltage conversion circuit with the operating power supply voltage and outputting a voltage for controlling the substrate potential of the current-voltage conversion circuit so that the voltage value generated by the current-voltage conversion circuit is equal to the operating power supply voltage value of the main circuit, wherein the substrate potential control circuit controls a substrate potential of a MOS transistor in the main circuit, and the constant current generation circuit generates a plurality of constant current values, and selectively outputs one of the plurality of constant current values.