Patent ID: 7423446

Claim:
A method for characterizing threshold voltage variation in an array of devices, the method comprising: selecting a device within said array as a device under test; providing a predetermined current through a channel of said device under test while providing a predetermined channel voltage across said channel and a predetermined gate voltage at a gate terminal of said device under test; measuring a source voltage at a source terminal of said device under test; repeating said selecting, said providing and said measuring for multiple devices within said array to obtain a set of source voltage measurements; computing a set of threshold voltages for said multiple devices from said set of source voltage measurements by applying an adjustment value; and analyzing said set of threshold voltages to generate a description of said threshold voltage variation, wherein said providing a predetermined current through a channel of said device while providing a predetermined channel voltage across said channel is performed by coupling an input of a source follower circuit to said source terminal of said device under test and coupling an output of said source follower circuit to a drain terminal of said device under test.