Dynamic sleep transistor and body bias for active leakage power control of microprocessors

In order to manage the active power consumption of high-performance digital designs, active leakage control techniques are required to provide significant leakage power savings coupled with fast time constants for entering and exiting idle mode. In this paper, dynamic sleep transistors and body bias are used in conjunction with clock gating to control active leakage for a 32-bit integer execution core in 130-nm CMOS technology. Measurements on pMOS sleep transistor reveal that lowest-leakage state is reached in less than 1 μs, resulting in 37× reduction in leakage power, while reactivation of block is achieved in less than two clock cycles. PMOS body bias reduces leakage power by 2× with no performance penalty, and similar reactivation time. Power measurements at 4 GHz, 1.3 V, 75°C demonstrate 8% total power reduction using dynamic body bias and 15% power reduction using a pMOS sleep transistor, for a typical activity profile.