Detecting interport faults in multiport static memories

Abstract

A multiport testing procedure capable of detecting faults that occur between static random access memory ports as well as traditional cells faults uncovers all possible faults and covers all cells in the memory, without placing architectural constraints on the memory. While executing a test sequence on one port of the memory array, concurrent memory accesses are performed through other ports in the memory. If a fault exists between the port under test and any other port, then the concurrent operations interfere with the values read and/or written on the port under test, and the test uncovers the fault. Thus, for any one test port, the interport test requires only as many memory operations as the associated single port test, keeping test time to a minimum. One embodiment detects faults between the test port, which is a read/write port, and any other port, including read ports and write ports, comprising six passes through the memory. Another embodiment detects faults between write ports, comprising four memory passes. An embodiment of a memory test circuit is disclosed that executes the multiport tests.