Credence Systems Corporation

David Scott

Brian J Arkin

Garry C Gillette

Ha Nguyen

A parallel processing pattern generation system for an integrated circuit tester includes two pattern memories, a main pattern generator, and two auxiliary pattern generators. Each pattern memory may receive and store data patterns from a host computer before the test. All three pattern generators may produce data pattern sequences in a variety of ways by executing separately stored algorithmic programs. The pattern sequences generated by each of the two auxiliary pattern generators separately address the two pattern memories so that either one or both of the two pattern memories may read out pattern data during a test. The main pattern generator includes a routing circuit for receiving as inputs a portion of the pattern data generated by the main pattern generator itself and the pattern data read out of the two pattern memories. The routing circuit, controlled by another portion of the pattern data produced by the main pattern generator, selects from among its inputs on a bit-by-bit, cycle-by-cycle basis to provide pattern data for controlling tester activities during each cycle of a test.

Parallel processing pattern generation system for an integrated circuit

An integrated circuit tester includes a host computer, a pattern generator and a set of tester circuits. The tester circuits perform test activities on an integrated circuit in response to sequences of test control data arriving via a set of data lines. The host computer may write parameter control data into the tester circuits via a bus telling the tester circuits how to adjust various parameters of test activities to be performed in response to a next arriving sequence of test control data. The host computer is also linked to the pattern generator via that same bus and writes pattern control data into the pattern generator via the bus. The pattern control data tells the pattern generator to generate alternating sequences of test control data and pattern control data. As it is generated, each test control data sequence is delivered to the tester circuits via the data lines to tell the tester circuits how to carry out a sequence of test activities. As each parameter control data sequence is generated, the parameter control data is written into the tester circuits via the bus to set the test parameters for a next sequence of test activities to be performed. Thus once programmed with pattern control data from the host, the pattern generator can cause the tester circuits to carry out a sequence of tests and to appropriately adjust their test parameters before each test without further assistance from the host computer.

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David Scott