Comparison of adaptive body bias (ABB) and adaptive supply voltage (ASV) for improving delay and leakage under the presence of process variation

Process variations as a percentage of nominal delay and power consumption are becoming more and more severe with continuing scaling of VLSI technology. The worsening process variation causes increased variability in performance, power, and reliability of VLSI circuits. Thus, performance and power consumption targets obtained during the design phase of VLSI circuits may significantly deviate from that of actual silicon resulting in significant yield losses. Adaptive body bias (ABB) has been shown to be an effective method of postsilicon tuning to reduce variability under the presence of process variation. Post silicon tuning can also be accomplished by using adaptive supply voltage (ASV). This paper compares the effectiveness of ABB and ASV in reducing variability and improving performance and power, and thus, yield.