BTI aware thermal management for reliable DVFS designs

In this paper, we show that dynamic voltage and frequency scaling (DVFS) designs, together with stress-induced BTI variability, exhibit high temperature-induced BTI variability, depending on their workload and operating modes. We show that the impact of temperature-induced variability on circuit lifetime can be higher than that due to stress and exceed 50% over the value estimated considering the circuit average temperature. In order to account for these variabilities in lifetime estimation at design time, we propose a simulation framework for the BTI degradation analysis of DVFS designs accounting for workload and actual temperature profiles. A profile is generated considering statistically probable workload and thermal management constraints by means of the HotSpot tool. Using the proposed framework we explore the expected lifetime of the ethernet circuit from the IWLS05 benchmark suite, synthesized with a 32nm CMOS technology library, for various thermal management constraints. We show that margin-based design can underestimate or overestimate lifetime of DVFS designs by up to 67.8% and 61.9%, respectively. Therefore, the proposed framework allows designers to select appropriately the dynamic thermal management constraints in order to tradeoff long-term reliability (lifetime) and performance with upto 35.8% and 26.3% higher accuracy, respectively, against a temperature-variability unaware BTI analysis.