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

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... 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.