A Framework for Optimizing Thermoelectric Active Cooling Systems

Thin-film thermoelectric cooling is a promising technology for mitigating heat dissipation in high performance chips. In this paper, we present an optimization framework for an active cooling system that is comprised of an array of thin-film thermoelectric coolers. We observe a set of constraints of the cooling system design. Firstly, integrating an excessive amount of coolers increases the chip package cost. Moreover, thermoelectric coolers are active devices, which dissipate heat in the chip package when they are in operation. Hence, setting the supply current level to operate the cooler improperly can actually lead to overheating of the chip package. Besides, the supply current needs to be delivered to the integrated cooler devices via dedicated pins. However, extra pins available on high-performance chip packages are limited. Observing these constraints, we propose an optimization framework for configuring the active cooling system, which minimizes the maximum silicon temperature. This includes determining the amount of coolers to deploy and their locations, the mapping of supply pins to the coolers, and determining the current levels of each pin. We propose algorithms to tackle the optimal configuration problem. We found that only a small portion of the silicon die needs to be covered by TEC devices (18% on average). Our experiments show that our algorithms are able to reduce the temperatures of the hot spots by as much as 10.6 degrees C (compared to the cases without integrated thermoelectric coolers). The average temperature reduction is 8.6 degrees C when 4 dedicated pins are available on the package. The total power consumption of the resulting active cooling system is reasonably small (similar to 2 W). Our experiments also reveal that our framework maximizes the efficiency of the cooling devices. In the ideal case where hundreds of pins are available to tune the supply level of each individual cooler, the additional average reduction of the hot spot temperature is only 0.3 degrees C.