Patent ID: 8692571
Filing Date: 2014-04-08
Classification: G01R

Abstract:
1. An apparatus for assessing operating characteristics of metal oxide semiconductor devices, comprising: a metal oxide semiconductor (MOS) device of a first polarity; a switching network operable to couple to the MOS device selected combinations drain/source bias and gate input voltage, wherein the selected combinations include application of nominal voltage and current conditions and include application of enhanced stress conditions, said enhanced stress conditions temporarily or permanently altering the operating characteristics of the MOS device; a current source circuit comprising said MOS device of said first polarity and further comprising a complementary MOS device of a second polarity, wherein the MOS devices of said first and second polarities are coupleable at a junction as a complementary pair, in series with one another and across a potential difference, to provide a current source to a load coupled to the junction; an oscillator comprising a plurality of stages in a cascaded loop, wherein the oscillator produces a signal that varies in frequency at least partly as a function of a bias level applied to the oscillator from a voltage supply; and, a bias control circuit coupled to supply the oscillator with power from the voltage supply, wherein the bias control circuit has a control input coupled to the junction of the complementary pair, such that the oscillator frequency differs between the nominal voltage and current conditions versus the enhanced stress conditions of the MOS device.