Method and apparatus for selectively compacting test responses
First Claim
1. An apparatus used in testing of an integrated circuit, comprising:
- a circuit under test that is part of the integrated circuit;
at least one spatial compactor to compress test responses from the circuit under test; and
a selector circuit coupled between the circuit under test and the spatial compactor that masks one or more of the test responses that are received from the circuit under test.
2 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus to compact test responses containing unknown values or multiple fault effects in a deterministic test environment. The proposed selective compactor employs a linear compactor with selection circuitry for selectively passing test responses to the compactor. In one embodiment, gating logic is controlled by a control register, a decoder, and flag registers. This circuitry, in conjunction with any conventional parallel test-response compaction scheme, allows control circuitry to selectively enable serial outputs of desired scan chains to be fed into a parallel compactor at a particular clock rate. A first flag register determines whether all, or only some, scan chain outputs are enabled and fed through the compactor. A second flag register determines if the scan chain selected by the selector register is enabled and all other scan chains are disabled, or the selected scan chain is disabled and all other scan chains are enabled. Other embodiments allow selective masking of a variable number of scan chain outputs.
56 Citations
21 Claims
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1. An apparatus used in testing of an integrated circuit, comprising:
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a circuit under test that is part of the integrated circuit;
at least one spatial compactor to compress test responses from the circuit under test; and
a selector circuit coupled between the circuit under test and the spatial compactor that masks one or more of the test responses that are received from the circuit under test. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for selectively compacting test responses of a circuit under test, comprising:
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receiving N test responses from scan chains in the circuit under test;
selectively preventing between 0 and N of the test responses from being passed to a spatial compactor while allowing the remaining test responses to be passed to the spatial compactor; and
spatially compacting the test responses passed to the spatial compactor. - View Dependent Claims (13, 14, 15, 16, 17)
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18. An apparatus used in testing of integrated circuits, comprising:
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scan chains within the integrated circuit;
a selector circuit coupled to the scan chains; and
a spatial compactor coupled to the selector circuit. - View Dependent Claims (19, 20, 21)
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Specification