Temperature-adaptive body-bias and supply voltage scaling for enhanced energy efficiency in nano-CMOS circuits

Temperature dependent propagation delay characteristics of CMOS circuits will experience a complete reversal in the near future. Contrary to the older technology generations, the speed of standard zero-body-biased circuits in a 32 nm CMOS technology is enhanced when the temperature is increased at the nominal supply voltage. The enhancement of circuit speed provides new opportunities to lower the energy consumed by active circuits at elevated temperatures. Temperature-adaptive supply and threshold voltage tuning techniques are proposed in this paper to reduce the high temperature active mode energy consumption without degrading the circuit speed. Results indicate that the energy consumption can be lowered by up to 21% by dynamically scaling the supply voltage at elevated temperatures. An alternative technique based on temperature-adaptive reverse body-bias exponentially reduces the leakage currents as well as the parasitic junction capacitances of the MOSFETs. The temperature-adaptive threshold voltage tuning through reverse body-bias yields an active mode energy reduction by up to 29.8% as compared to the standard zero body-biased circuits at high temperatures.