Component fault localization using switching current measurements

Conventional manufacturing/system tests point to a set of logically equivalent faults and not the exact fault within a faulty component. In this paper, we show that during testing, measuring the current drawn by a faulty component aids in identifying the exact manifested fault within it. We propose to partition the chip's power grid based on the chip's component partitions, and dedicate a external supply pin to each component partition. In order to minimize the cost associated with the external measurement circuitry, we reuse the scan resources available within the flip-flop to repeatedly apply the desired test-pattern pair, so that the average current measured during the launch-to-capture window, is equal to the same over a long period of time. The proposed technique is validated by simulating the power-grid and the modified flip-flop using SPICE circuit simulator. The proposed technique, when applied to several component benchmark circuits, helped to localize almost all the logically equivalent faults.