Observation of one-fifth-of-a-clock wake-up time of power-gated circuit

The wake-up time of zigzag super cut-off CMOS (ZSCCMOS) is measured using a functional block for the first time. The measurement method is established and the measured wake-up time is 16% of the cycle time for a 16-bit Brent-Kung adder. The wake-up time corresponds to a three 2-input NAND delay. The delay overhead and leakage current reduction of ring oscillators are also measured for the first time. Leakage reduction by a factor of 100 to 1000 is possible for dormant circuit blocks. Thus ZSCCMOS is shown to be effective as a clock-gating substitute.