Memory test system having a pattern generator for a multi-bit test
First Claim
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1. A semiconductor memory test system, comprising:
- an address generator for generating an address signal and supplying said generated address signal to a memory under test;
a data generator for generating test data and supplying said generated test data to the memory under test;
a clock generator for providing a clock signal to the address generator and to the memory under test;
a controller for controlling and coordinating operation of the address generator, the data generator and the clock generator for writing the test data into and reading the test data out from the memory under test;
a logic comparator for comparing an output of the memory under test with expected data, for determining whether the memory under test functions correctly; and
a logic circuit coupled to receive the test data and a multi-bit test control signal asserted during multi-bit testing for providing said expected data to the logic comparator responsive to assertion of the multi-bit test control signal.
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Abstract
A semiconductor memory testing methods and apparatus are arranged to accommodate a multi-bit mode of testing operation in which the memory under test itself includes internal peripheral circuits for comparing the contents of memory cells for multi-bit testing, and outputting a single-bit indicative of whether or not said multiple cells have the same state. The present invention includes methods and apparatus for determining the polarity of a memory cell under test, and taking that polarity into account informing expected data to be compared to the output of the memory under test.
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Citations
12 Claims
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1. A semiconductor memory test system, comprising:
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an address generator for generating an address signal and supplying said generated address signal to a memory under test; a data generator for generating test data and supplying said generated test data to the memory under test; a clock generator for providing a clock signal to the address generator and to the memory under test; a controller for controlling and coordinating operation of the address generator, the data generator and the clock generator for writing the test data into and reading the test data out from the memory under test; a logic comparator for comparing an output of the memory under test with expected data, for determining whether the memory under test functions correctly; and a logic circuit coupled to receive the test data and a multi-bit test control signal asserted during multi-bit testing for providing said expected data to the logic comparator responsive to assertion of the multi-bit test control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of testing a semiconductor memory device under test (MUT) having an on-board multi-bit test logic circuit that outputs a memory output bit having a predetermined logic state when all of the bits read out of a selected group of cells in the memory device have the same logic state, the method comprising the steps of:
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generating a current address for accessing a selected group of cells in the MUT; generating a test bit; determining whether the current address corresponds to a true polarity memory cell or to a complement polarity memory cell; if the current address corresponds to a complementary polarity memory cell, complementing the test bit to form a pattern generator output bit; if the current address corresponds to a true polarity memory cell, providing the test bit as the pattern generator output bit; writing the pattern generator output bit to all of the selected group of cells in the MUT; reading the memory output bit to determine whether or not all of the bits read out of the selected group of cells in the memory device have the same logic state; forcing the expected data bit ED to a selected state; and comparing the memory output bit to the expected data bit to determine whether the MUT has a defect among the selected group of cells. - View Dependent Claims (9, 10)
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11. A test bit pattern generator for use in testing a semiconductor memory device comprising:
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an address generator for generating an address signal for addressing a memory device under test; a data generator for generating test data to write into the memory under test; a clock generator for clocking said memory under test and the address generator; a controller for controlling said address generator, said data generator and said clock generator for writing the test data into and reading the test data out from the memory under test; expected data (ED) means for forming expected data responsive to both the test data and the address signal for comparison to the data read out of the memory under test. - View Dependent Claims (12)
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Specification