International Business Machines Corporation

Thomas E Obremski

Donald Lawrence Wheater

Jeffrey H Dreibelbis

Erik A Nelson

William R Corbin

Laura S Chadwick

Toshiharu Saitoh

Charles E Drake

Peter O Jakobsen

Brian Robert Kessler

Mark Adam Beiley

A system for testing a DRAM includes DRAM blocks, the system further includes a processor based built-in self test system for generating a test data pattern, for each DRAM block, performing a write of the test data pattern into the DRAM block, performing a pause for a predetermined period of time, and performing a read of a resulting data pattern from the DRAM block. For each DRAM block, the performing the write of the test pattern into the DRAM block is performed before the performing the pause for the predetermined period of time, and the performing the read of the resulting data pattern from the DRAM block is performed after the performing the pause for the predetermined period of time, and at least a portion of the pause for the predetermined period of time of two or more the DRAM blocks overlap in time.

Method for testing embedded DRAM arrays

Technique to perform logic and embedded memory tests using logic scan chain testing procedures in parallel with memory built in self test (BIST). This is accomplished with a combination of voltage isolation between memory and logic segments, and isolation between logic and memory test clocks. A test algorithm is introduced to enable and disable the scan chain operation during BIST operation.

Testing logic and embedded memory in parallel

A method and system for testing an embedded DRAM that includes DRAM blocks. The method including: generating a test data pattern in a processor based BIST system, for each DRAM block, performing a write of the test data pattern into the DRAM block, performing a pause for a predetermined period of time, and performing a read of a resulting data pattern from the DRAM block; where for each DRAM block, the write of the test data pattern into the DRAM block is performed before the pause, and the read of the resulting data pattern from each DRAM block is performed after the pause; where at least a portion of the pause of two or more of the DRAM blocks overlap in time; and for each DRAM block comparing the test data pattern to the resulting data pattern.

A programmable data generator for generating input test data to be applied to a semiconductor memory array is disclosed. In an exemplary embodiment of the invention, the data generator includes a programmable address scramble register which has a plurality of storage locations associated therewith. The plurality of storage locations corresponds to array address bits associated with an address generator. A first exclusive OR (XOR) logic structure is coupled to the address generator and the address scramble register, wherein the first XOR logic structure generates an address-dependent, data scramble output signal that ultimately determines a data pattern to be applied to the memory array.

Programmable built-in self test (BIST) data generator for semiconductor memory devices

A method for generating a selected subset of memory addresses associated with a semiconductor memory array is disclosed. In an exemplary embodiment of the invention, the method includes configuring an address counter to generate addresses corresponding to locations within the memory array. A mask register is programmed with a series of masking bits, the value of the masking bits determining whether corresponding address bits in the address counter are masked or not masked. Any of the address bits in the address counter corresponding to a masked bit are masked from a counting operation performed by the address counter, thereby causing the address counter to generate the selected subset of memory addresses.

Method and apparatus for ram built-in self test (BIST) address generation using bit-wise masking of counters

A small number of redundant circuits are freely allocable to any of a plurality of partitions or systems within an integrated circuit, such as a large dynamic random access memory (DRAM) consistent with the provision of parallel simultaneous refresh of corresponding addresses in all partitions or systems thereof. A valid address of a redundant circuit substituted for a partial address of a circuit in any partition or system is detected to disable refresh of that address in all partitions. The partition in which the substitution has been made is sensed and the disablement of refresh of all other partitions is overridden so that all partitions or systems in which a substitution has not been made may be refreshed concurrently with the substituted redundant circuit.

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South Burlington, VT, United States of America

Thomas E Obremski