Patent ID: 7532078

Claim:
A computer-controlled method for characterizing transistors in a test circuit including a ring oscillator and interfaced to a computer system the method comprising: conducting operating current to/from said ring oscillator from a first virtual power supply rail; conducting current to/from said first virtual power supply rail through a first plurality of transistors, each having a gate controlled by an output of a corresponding one of a first plurality of programmable elements controlled by said computer system; setting first states of said first plurality of programmable elements under control of said computer system such that individual ones of said first plurality of transistors are enabled; measuring an output frequency of said ring oscillator for each of said first states of said plurality of programmable elements set by said setting and storing results of said measuring; and generating results in conformity with results of said measuring in a memory of said computer system, whereby variation of characteristics of said plurality of transistors is revealed.