Scan multiplexing for increasing the effective scan data exchange rate

Abstract

Simultaneously increasing the effective frequency of scanning operations and increasing memory capacity can be achieved by multiplexing multiple state data into each tester memory location. A system includes a source for providing scan-in sequences of state data as input stimuli into a device under test (DUT) and expected scan-out sequences of state data. A vector processor receives the scan-in sequences and expected scan-out sequences and enables multiplexed state data exchanges in which the multiple multiplexed state data vectors are manipulated at the tester cycle rate, while the DUT manipulates the bits at its faster device cycle rate. For a multiplexing factor of m, the device cycle rate may be m times the tester cycle rate. The selection of the multiplexing factor is based upon the storage capacity of individual tester memory locations and upon enabling the effective vector exchange rate to be m times the tester cycle rate.