Process parameter extraction

摘要

An apparatus includes a test circuit, a first counter and a second counter. The test circuit is fabricated on a semiconductor substrate to generate an oscillating signal. The oscillating signal has a frequency that is dependent on at least in part a parameter of a process used to fabricate the test circuit. The first counter measures a time interval, and the second counter is coupled to the first counter to count a number of periods of the oscillating signal during the time interval.