1. Jun Seomun, Insup Shin, Youngsoo Shin Dept. of Electrical Engineering, KAIST DAC’ 10

2.  Introduction  Problem formulation  Algorithm  Experiments  Conclusion

3.  Active leakage is much larger than standby leakage (e.g. about 10× for 100 MHz frequency in room temperature [2]).  The large proportion of active leakage in total active power consumption, e.g. 30% [3, 4] in 65-nm technology.

4.  Active mode power gating (AMPG) [7] has been proposed to extend the application of power gating to reducing active leakage.

5.  Active leakage

7.  Input : ◦ A sequential circuit, which has clock-gating signals EN1,EN2,...,ENn. ◦ Signal ENi enables or disables a clock to a set of flip-flops Fi.  Subject : ◦ Derive a set of gates Gi that are power-gated by ENi ◦ Meet three constraints:  Functional Constraint  Timing Constraint  Current Constraint

10. clk EN1

11.  Wakeup time

12.  Modeling of discharge current 1

13.  Estimation of MDC

14.  Estimation of ADC ◦ p1 and p2 : the probability of signal being at logic high ◦ t1 and t2: transition probabilities ◦ these can be obtained by propagating signal probabilities at primary inputs [14]

16.  ISCAS benchmark. which was synthesized [15] with commercial 1.1 V, 45-nm bulk CMOS technology.

18.  They have presented a method to synthesize AMPG circuits. The key components in synthesis are the three constraints.  The amount of saving in active leakage, 16% on average.  A new placement algorithm specific to AMPG circuits or taking physical design into account during AMPG synthesis may alleviate this impact.