Total power requirements for near-future refrigerated systems

As feature dimensions of processors shrink to 100 nanometers and smaller, leakage current becomes a significant part of total power dissipation. The magnitude of power dissipated as leakage current can approach half that of the active current at higher junction temperatures. Leakage current exhibits a strong exponential relationship with temperature. Reduction of junction temperatures from a traditional value of 85 C to a near-ambient value of 25 C can reduce leakage current to a fraction of its usual value, and total power by nearly one-third. To date, refrigeration has been used to increase operating frequency and improve reliability, at the cost of considerable power consumption. At finer feature dimensions, the energy saved by reduction of junction temperature is comparable to that used by the refrigeration system. Realistic values of refrigeration performance, representative of current equipment and refrigerants, are used to perform a case study of a typical near-future processor. Leakage, active and refrigeration power requirements over a junction temperature range from 85 to 25 C are quantified.