Advanced thermal sensing circuit and test techniques used in a high performance 65nm processor

Traditional inaccuracies during manufacturing test of the thermal sensor circuit require excessive guard-bands. These guard-bands increase the chance of unnecessary microprocessor throttling and could introduce a less-than optimum power and thermal design envelope. Circuit techniques that minimize these errors are discussed, including an improved temperature-independent voltage pump, a remote thermal sensing scheme for hot-spot to sensor offset reduction, and a self-heating error calibration method. Experimental data obtained on a high performance 65nm Intel® Pentium® 4 microprocessor demonstrates the feasibility and effectiveness of these techniques, providing a combined potential accuracy improvement of up to 17°C.