Adaptive techniques for overcoming performance degradation due to aging in digital circuits

Negative Bias Temperature Instability (NBTI) in PMOS transistors has become a major reliability concern in present-day digital circuit design. Further, with the recent usage of Hf-based high-k dielectrics for gate leakage reduction, Positive Bias Temperature Instability (PBTI), the dual effect in NMOS transistors has also reached significant levels. Consequently, designers are required to build in substantial guard- bands into their designs, leading to large area and power overheads, in order to guarantee reliable operation over the lifetime of a chip. We propose a guard-banding technique based on adaptive body bias (ABB) and adaptive supply voltage (ASV), to recover the performance of an aged circuit, and compare its merits over previous approaches.