PMScan : A power-managed scan for simultaneous reduction of dynamic and leakage power during scan test

In sub-70 nm technologies, leakage power becomes a significant component of the total power. Designers address this concern by extensive use of adaptive voltage scaling techniques to reduce dynamic as well as leakage power. Low-power scan test schemes that have evolved in the past primarily address dynamic power reduction, and are less effective in reducing the total power. We propose a power-managed scan (PMScan) scheme which exploits the presence of adaptive voltage scaling logic to reduce test power. We also discuss some practical implementation challenges that arise when the proposed scheme is employed on industrial designs. Experimental results on benchmark circuits and industrial designs show a significant reduction in dynamic and leakage power. The proposed method can also be used as a vehicle to trade-off test application time with test power by suitably adjusting the scan shift frequency and scan-mode power supplies.