US Patent 7560975 Semiconductor device

The well voltage of a CMOS circuit having low-threshold-voltage MOSFETs is controlled when the power supply is turned on, during normal operation, and when the supply voltage is cut off. The CMOS circuit can thus operate stably with lower power consumption, because latching-up is reduced when the supply voltage is applied to the CMOS circuit or when the supply voltage is cut off, and subthreshold current is decreased during normal operation.