Patent ID: 7486583

Claim:
A self-refresh period measurement circuit of a semiconductor device comprising: a delay device configured to receive an oscillation signal that is periodically enabled after a self-refresh signal is enabled, to allow a self-refresh operation to be performed, and delay the received oscillation signal by a unit self-refresh period to output a delayed oscillation signal; a period measurement start signal generator configured to receive the self-refresh signal and the oscillation signal, and generate a period measurement start signal for setting a time that the oscillation signal is enabled for the first time as a start time for measurement of a self-refresh period; and a refresh period output unit configured to receive the period measurement start signal and the delayed oscillation signal from the delay device, and generate a refresh period output signal that is enabled for a period from a time that the period measurement start signal is enabled to a time that the delayed oscillation signal is enabled for the first time.