Patent ID: 6924679

Claim:
A power supply voltage control apparatus, comprising: a semiconductor circuit having transmission paths and receiving a power supply voltage to operate, an input signal generation circuit able to change a phase difference of both signals in accordance with a control signal when generating a reference signal and an input signal from an input clock signal, a monitor circuit having a characteristic between a power supply voltage and delay equivalent to that of a critical path of the semiconductor circuit, receiving and propagating the input signal from the input signal generation circuit, and outputting a delayed signal to be delayed exactly by a time equivalent to delay of the critical path, a delay detection circuit for receiving the delayed signal from the monitor circuit and the reference signal from the input signal generation circuit to detect a delay of the delayed signal relative to the reference signal, and a power supply voltage control circuit for controlling the power supply voltage to be supplied to the semiconductor circuit and the monitor circuit based on a result detected by the delay detection circuit.