International Business Machines Corporation

David P Monty

Steven William Tomashot

David G Chapman

Timothy E Fiscus

Erik A Nelson

Alan D Norris

William E Corbin, Jr

William R Corbin

A method for testing the data strobe window (DQS) and data valid window (tDV) of a memory device (e.g., a DDR-type memory device) using the window strobe of a testing system.

Method for guaranteeing a minimum data strobe valid window and a minimum data valid window for DDR memory devices

To overcome these problems, the present invention generates two window strobes and uses the two window strobes to determine if skew between two signals meets predetermined criteria. One of the window strobes is used to test one of the signals, and the other window strobe is generated relative to the first window strobe. The second window strobe tests the other signal (or signals, if they are data signals). From the tests of the two window strobes, it can be determined if the skew between the first and second signals meets predetermined criteria. In particular, the two window strobes are placed relative to each other and to the signals being tested in such a way that when both window strobes indicate passing conditions, skew between the two signals is guaranteed.

Method for testing and guaranteeing that skew between two signals meets predetermined criteria

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Essex Junction, VT, United States of America

David P Monty