Abstract: Disclosed below are representative embodiments of methods, apparatus, and systems used to generate test patterns for testing integrated circuits. Embodiments of the disclosed technology can be used to provide a low power test scheme and can be integrated with a variety of compression hardware architectures (e.g., an embedded deterministic test (“EDT”) environment). Certain embodiments of the disclosed technology can reduce the switching rates, and thus the power dissipation, in scan chains with no hardware modification. Other embodiments use specialized decompression hardware and compression techniques to achieve low power testing.

Abstract: Chain or logic diagnosis resolution can be enhanced in the presence of limited failure cycles using embodiments of the various methods, systems, and apparatus described herein. For example, pattern sets can be ordered according to a diagnosis coverage figure, which can be used to measure chain or logic diagnosability of the pattern set. Per-pin based diagnosis techniques can also be used to analyze limited failure data.

Abstract: Test patterns for at-speed scan tests are generated by filling unspecified bits of test cubes with functional background data. Functional background data are scan cell values observed when switching activity of the circuit under test is near a steady state. Hardware implementations in EDT (embedded deterministic test) environment are also disclosed.

Abstract: Disclosed herein are exemplary embodiments of a so-called “X-press” test response compactor. Certain embodiments of the disclosed compactor comprise an overdrive section and scan chain selection logic. Certain embodiments of the disclosed technology offer compaction ratios on the order of 1000×. Exemplary embodiments of the disclosed compactor can maintain about the same coverage and about the same diagnostic resolution as that of conventional scan-based test scenarios. Some embodiments of a scan chain selection scheme can significantly reduce or entirely eliminate unknown states occurring in test responses that enter the compactor. Also disclosed herein are embodiments of on-chip comparator circuits and methods for generating control circuitry for masking selection circuits.

Abstract: The present disclosure describes embodiments of a compactor for compressing test results in an integrated circuit and methods for using and designing such embodiments. The disclosed compactors can be utilized, for example, as part of any scan-based design. Moreover, any of the disclosed compactors can be designed, simulated, and/or verified in a computer-executed application, such as an electronic-design-automation (“EDA”) software tool. Embodiments of a method for diagnosing faults in the disclosed compactor embodiments are also described.

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.

Abstract: A method is disclosed for the automated synthesis of phase shifters—circuits used to remove effects of structural dependencies featured by pseudo-random test pattern generators driving parallel scan chains. Using a concept of duality, the method relates the logical states of linear feedback shift registers (LFSRs) and circuits spacing their inputs to each of the output channels. The method generates a phase shifter network balancing the loads of successive stages of LFSRs and satisfying criteria of reduced linear dependency, channel separation and circuit complexity.

Abstract: Disclosed below are representative embodiments of methods, apparatus, and systems used to generate test patterns for testing integrated circuits. Embodiments of the disclosed technology can be used to provide a low power test scheme and can be integrated with a variety of compression hardware architectures (e.g., an embedded deterministic test (“EDT”) environment). Certain embodiments of the disclosed technology can reduce the switching rates, and thus the power dissipation, in scan chains with no hardware modification. Other embodiments use specialized decompression hardware and compression techniques to achieve low power testing.

Abstract: The test data compression scheme is based on deterministic vector clustering. Test cubes that feature many similar specified bits are merged into a parent pattern in the presence of conflicts. The parent pattern along with a control pattern and incremental patterns representing conflicting bits are encoded efficiently. A tri-modal decompressor may be used to decompress the test data.

Abstract: Fault diagnosis techniques for non-volatile memories are disclosed. The techniques are based on deterministic partitioning of rows and/or columns of cells in a memory array. Through deterministic partitioning, signatures are generated for identification of failing rows, columns and single memory cells. A row/column selector or a combined row and column selector may be built on chip to implement the process of deterministic partitioning. An optional shadow register may be used to transfer obtained signatures to an automated test equipment (ATE).

Abstract: As described herein, circuit testing algorithms, or portions thereof, can be executed in a distributed manner so that their execution can be over a network of processors. In one aspect, the results that are obtained by such distributed execution are ensured to be consistent with the results that would be obtained by executing them in a non-distributed manner. Thus, in one aspect, the algorithms, or portions thereof, have to be made distributable. The algorithms, or portions thereof, are made distributable by isolating any random number generation therewith to be independent of each other. This isolation applies to any random number generation associated with different call instances of the same algorithm as well. In one aspect, the isolation is accomplished by ensuring that the calculation of random number sequences for the algorithms, or portions thereof, is not dependent on random number sequences calculated for the others or between call instances of the same algorithm.

Abstract: The present disclosure describes embodiments of a compactor for compressing test results in an integrated circuit and methods for using and designing such embodiments. The disclosed compactors can be utilized, for example, as part of any scan-based design. Moreover, any of the disclosed compactors can be designed, simulated, and/or verified in a computer-executed application, such as an electronic-design-automation (“EDA”) software tool. Embodiments of a method for diagnosing faults in the disclosed compactor embodiments are also described.

Abstract: Disclosed herein are representative embodiments of methods, apparatus, and systems used for generating test patterns as may be used as part of a test pattern generation process (for example, for use with an automatic test pattern generator (ATPG) software tool). In one exemplary embodiment, hold probabilities are determined for state elements (for example, scan cells) of a circuit design. A test cube is generated targeting one or more faults in the circuit design. In one particular implementation, the test cube initially comprises specified values that target the one or more faults and further comprises unspecified values. The test cube is modified by specifying at least a portion of the unspecified values with values determined at least in part from the hold probabilities and stored.

Abstract: Disclosed below are representative embodiments of methods, apparatus, and systems used to generate test patterns for testing integrated circuits. Embodiments of the disclosed technology can be used to provide a low power test scheme and can be integrated with a variety of compression hardware architectures (e.g., an embedded deterministic test (“EDT”) environment). Certain embodiments of the disclosed technology can reduce the switching rates, and thus the power dissipation, in scan chains with no hardware modification. Other embodiments use specialized decompression hardware and compression techniques to achieve low power testing.

Abstract: Methods, apparatus, and systems for performing fault diagnosis are disclosed herein. In one exemplary embodiment, a failure log is received including entries indicative of compressed test responses to chain patterns and compressed test responses to scan patterns. A faulty scan chain in the circuit-under-test is identified based at least in part on one or more of the entries indicative of the compressed test responses to chain patterns. One or more faulty scan cell candidates in the faulty scan chain are identified based at least in part on one or more of the entries indicative of the compressed test responses to scan patterns. The one or more identified scan cell candidates can be reported. Computer-readable media comprising computer-executable instructions for causing a computer to perform any of the disclosed methods are also provided. Likewise, computer-readable media storing lists of fault candidates identified by any of the disclosed methods are also provided.

Abstract: A method is disclosed for the automated synthesis of phase shifters—circuits used to remove effects of structural dependencies featured by pseudo-random test pattern generators driving parallel scan chains. Using a concept of duality, the method relates the logical states of linear feedback shift registers (LFSRs) and circuits spacing their inputs to each of the output channels. The method generates a phase shifter network balancing the loads of successive stages of LFSRs and satisfying criteria of reduced linear dependency, channel separation and circuit complexity.

Abstract: Disclosed herein are representative embodiments of methods, apparatus, and systems used for generating test patterns as may be used as part of a test pattern generation process (for example, for use with an automatic test pattern generator (ATPG) software tool). In one exemplary embodiment, hold probabilities are determined for state elements (for example, scan cells) of a circuit design. A test cube is generated targeting one or more faults in the circuit design. In one particular implementation, the test cube initially comprises specified values that target the one or more faults and further comprises unspecified values. The test cube is modified by specifying at least a portion of the unspecified values with values determined at least in part from the hold probabilities and stored.

Abstract: Described herein are methods and systems for distributed execution of circuit testing algorithms, or portions thereof. Distributed processing can result in faster processing. Algorithms or portions of algorithms that are independent from each other can be executed in a non-sequential manner (e.g., parallel) over a network of plurality of processors. The network includes a controlling processor that can allocate tasks to other processors and conduct the execution of some tasks on its own. Dependent algorithms, or portions thereof, can be performed on the controlling processor or one of the controlled processors in a sequential manner. For algorithms that are highly sequential in nature, portions of algorithms can be modified to delay the need for dependent results between algorithm portions by creating a rolling window of independent tasks that is iterated.

Abstract: A method is disclosed for the automated synthesis of phase shifters—circuits used to remove effects of structural dependencies featured by pseudo-random test pattern generators driving parallel scan chains. Using a concept of duality, the method relates the logical states of linear feedback shift registers (LFSRs) and circuits spacing their inputs to each of the output channels. The method generates a phase shifter network balancing the loads of successive stages of LFSRs and satisfying criteria of reduced linear dependency, channel separation and circuit complexity.

Abstract: Disclosed below are representative embodiments of methods, apparatus, and systems used to generate test patterns for testing integrated circuits. Embodiments of the disclosed technology can be used to provide a low power test scheme and can be integrated with a variety of compression hardware architectures (e.g., an embedded deterministic test (“EDT”) environment). Certain embodiments of the disclosed technology can reduce the switching rates, and thus the power dissipation, in scan chains with no hardware modification. Other embodiments use specialized decompression hardware and compression techniques to achieve low power testing.