Testability architecture and techniques for programmable interconnect

Abstract

Apparatus for testing for defects in the form of ohmic leakage in an antifuse element disposed between first and second conductors in an integrated circuit prior to formation of electronic circuits by a user, includes circuitry, responsive to signals provided to the integrated circuit from an external source, for temporarily connecting together a first group of the conductors to form a circuit path to the first conductor during a first time period. Circuitry, responsive to signals provided to the integrated circuit from an external source, is provided to temporarily connect together a second group of the conductors to form a circuit path to the second conductor during the first time period. Circuitry is provided to place an electrical charge onto the first conductor during a second time period within the first time period such that a selected dynamic first voltage potential is placed on the first conductor. Circuitry is provided to drive the second conductor to a second voltage potential different from the selected dynamic first voltage potential during a third time period subsequent to the second time period and within the first time period, wherein the difference between the first voltage potential and the second voltage potential is less than the voltage necessary to cause degradation of the antifuse element. Circuitry is provided to sense the voltage on the first conductor at a predetermined time after the start of the third time period and within the first time period. Circuitry is provided to store a signal related to the voltage on the first conductor at the predetermined time after the start of the third time period. Circuitry is provided to communicate the signal to an input/output pad of the integrated circuit.