Performance-temperature optimization by modulating the switching factor

Abstract

A system and method for modulating the switching factor of a circuit to control heating and which does not require modulation of the circuit's clock frequency. The switching factor refers to the fact that due to gating requirements, latency and data transfer characteristics, the rate at which a circuit's inputs are addressed is some fraction of the circuit clock frequency. Application can be made to many existing systems which incorporate single or multiple VLSI circuits such as superscalar microprocessors, parallel processors, DSPs, microcontrollers and MPEG decoders. A method for controlling a switching factor of a multi-functional unit processor includes the steps of: scheduling instructions stored in a memory for execution on each functional unit; generating a first temperature signal for a first functional unit and a second temperature signal for a second functional unit, each temperature signal being a function of a temperature associated with each functional unit; identifying the first functional unit and the second functional unit associated with each temperature signal, responsive to the generating step; comparing the first temperature signal with a first predetermined temperature threshold signal; generating a first temperature delay signal when the first temperature signal exceeds the first predetermined threshold, responsive to the comparison; and reducing the switching factor of the first functional unit according to the first temperature delay signal by delaying scheduling instructions for execution on the first functional unit. Further reduction in power dissipation may be achieved by using thermal feedback to cooperatively vary the voltage and frequency of a circuit.