Test converage of embedded memories on semiconductor substrates
First Claim
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1. A device for testing memory having separate write cycles and read cycles at a given port, comprising:
- first logic circuitry to generate and input first write data of a known value to memory during a write cycle,second logic circuitry to generate and apply second write data to said memory during a read cycle which second write data is different from said first write data written to memory during said write cycle, andthird logic circuitry to read data from memory during said read cycle.
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Abstract
The present invention provides a device for testing memory having write cycles and read cycles. A BIST state machine changes the data applied to the memory'"'"'s DI port during read cycles to a value different from that of the data stored in the currently addressed memory location. The BIST-generated expect data also is at a different value from that of data at the memory'"'"'s DI port and at the same value as the data stored at the current memory address location during read operations. With this arrangement, flush through defects can be detected which would not have been detectable by prior BIST machines.
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Citations
17 Claims
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1. A device for testing memory having separate write cycles and read cycles at a given port, comprising:
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first logic circuitry to generate and input first write data of a known value to memory during a write cycle, second logic circuitry to generate and apply second write data to said memory during a read cycle which second write data is different from said first write data written to memory during said write cycle, and third logic circuitry to read data from memory during said read cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of testing a memory using successive write and read cycles at a given point comprising the steps of:
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writing first write data of a known value to said memory for storage therein during a write cycle, applying second write data to said memory during a subsequent read cycle which second write data is different from said first write data, and reading data from said memory during said read cycle. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification