A system and method for determining the location of a particular device on
an integrated circuit chip is described. The system and method utilize
apparatus for detecting the emission of light during switching events of
devices in the circuit during the circuit's processing of an input
calculated to actuate the device whose location is desired. Light
emissions from the circuit can be temporally and spatially indexed so as
to allow deduction, in combination with the a priori knowledge of the
logical operation of the circuit, of the location of the desired element.
In another embodiment of the invention, a series of images of the circuit
can be accumulated, representing the circuit's response to a series of
different input signals, each input signal being designed to result in the
switching of the desired element. The series of images can be compared to
determine the location of the desired element. Also in accordance with the
invention, the elements to be located can be either actual functional
circuit elements, or fiducials added to the chip for test purposes.