On-die parameter extraction from path-delay measurements

Device-parameter estimation through path-delay measurement, which facilitates fast on-die performance prediction and diagnosis, is proposed. With the proposed technique, delays of a set of paths consisting of different logic cells are monitored. Based on the pre-characterized parameter to delay sensitivity, the process variation of a chip is estimated as an inverse problem. Discussion of desirable logic cell combination to form paths that maximize estimation accuracy is presented. Measurement of ring oscillator arrays composed of standard and customized logic cells resulted in consistent estimation of threshold voltages. Measurement accuracy is greatly enhanced by the proposed good logic cell combinations.