Abstract: Provided are a generation device and the like for generating a new vector whose volume can be reduced rapidly when an output pattern derived from a decompressor of a logic circuit under test includes an unspecified bit in relation to the logic circuit under test. The output pattern includes unspecified bits. In step SS1, classification unit classifies the unspecified bits and determines if an unspecified bit is an implied bit or not. The implied bit is an unspecified bit if its value is a logic value determined as logic value 0 or 1 relating to logic bits in the initial vector and according to a predetermined condition (such as compressibility) among bits in the initial vector derived from the upstream logic circuit 1. In step SS1, the unspecified bits which are not implied bits are classified as free bits. The classification unit classifies free bit sets in step SS2, and further classifies free bits to identify compatible free bit sets.

Abstract: A test pattern generation method for determining if a combinational portion 17 is defective, by applying test patterns to a semiconductor integrated circuit 10 and comparing responses to the test patterns with expected responses, the method including: a first step of generating test patterns having logic bits for detecting defects and unspecified bits; a second step of selecting critical paths 19, 19a, 19b generated by the application of the test patterns; a third step of identifying critical gates on the critical paths 19, 19a, 19b; and a fourth step of determining unspecified bits so that a critical capture transition metric, which indicates the number of the critical gates whose states are changed, is reduced; wherein by reducing the critical capture transition metric, output delays from the critical paths 19, 19a, 19b are prevented, and thereby false testing can be avoided.

Abstract: A method and system to automate scan synthesis at register-transfer level (RTL). The method and system will produce scan HDL code modeled at RTL for an integrated circuit modeled at RTL. The method and system comprise computer-implemented steps of performing RTL testability analysis, clock-domain minimization, scan selection, test point selection, scan repair and test point insertion, scan replacement and scan stitching, scan extraction, interactive scan debug, interactive scan repair, and flush/random test bench generation. In addition, the present invention further comprises a method and system for hierarchical scan synthesis by performing scan synthesis module-by-module and then stitching these scanned modules together at top-level. The present invention further comprises integrating and verifying the scan HDL code with other design-for-test (DFT) HDL code, including boundary-scan and logic BIST (built-in self-test).

Abstract: Provided are a generation device and the like for generating a test vector which can reduce capture power efficiently. The generation device 100 generates a test vector for a logic circuit by assigning logic values to each of a plurality of unspecified bits (X-bits) included in a test cube.

Abstract: Provided are a conversion device and others for converting a test vector set so as to reduce a logic value difference generated before and after scan capture in outputs of scan cells included in a full scan sequential circuit. A conversion device converts a test vector set corresponding to the full scan sequential circuit. The conversion device comprises a setting unit for setting a candidate bit which can be a don't care bit and a fixed bit which cannot be the don't care bit according to predetermined constraint conditions based on an input-output relationship in the logic circuit in order to identify the don't care bit identifiable as don't care from each test vector of the test vector set, and a logic value deciding unit for deciding a logic value for the don't care bit in view of a relationship in a plurality of bit pairs in relation to a test cube including the don't care bit identified by the setting unit.

Abstract: Provided are a generation device to reduce launch switching activity, yield loss risk, and power consumption of testing, even in the at-speed scan testing, even with a small number of don't-care (X) bits in input bits as in test compression, without any impact on test data volume, fault coverage, performance, and circuit design, by putting focus on internal lines in the circuit. The generation device includes a target internal line selection unit, a target internal line distinction unit, an identification unit that identifies a bit to be an unspecified bit and a bit to be a logic bit in the input bits, and an assignment unit that assigns a logic value 1 or a logic value 0 to unspecified bits in the input bits. The identification unit includes an unspecified bit identification unit and an input logic bit identification unit.

Abstract: A generation apparatus and the like for generating a test vector set capable of reducing differences in a logic value generated before and after a scan capture for outputs from scan cells included in a full-scan sequential circuit are provided. A generation apparatus 200 generating an initial test vector set 216 for a logic circuit includes a target vector identification unit 204 identifying a test vector satisfying a predetermined criterion and to be selected for the number of bits (the number of bit transitions) whose logic values differ before and after scan capture with respect to outputs from scan cells included in the sequential circuit, from among test vectors in the initial test vector set 216, and a test vector set conversion unit 206 converting the test vector identified by the test vector identification unit 204 and to be selected so as to reduce the number of bit transitions with respect to outputs from the scan cells included in the sequential circuit.

Abstract: A method and apparatus for testing or diagnosing faults in a scan-based integrated circuit using a unified self-test and scan-test technique. The method and apparatus comprises using a unified test controller to ease prototype debug and production test. The unified test controller further comprises using a capture clock generator and a plurality of domain clock generators each embedded in a clock domain to perform self-test or scan-test. The capture clocks generated by the capture clock generator are used to guide at-speed or reduced-speed self-test (or scan-test) within each clock domain. The frequency of these capture clocks can be totally unrelated to those of system clocks controlling the clock domains. This unified approach allows designers to test or diagnose stuck-type and non-stuck-type faults with a low-cost DFT (design-for-test) tester or a low-cost DFT debugger. A computer-aided design (CAD) method is further developed to realize the method and synthesize the apparatus.

Abstract: Provided are a diagnostic device and the like providing a favorable diagnosis result by further improving the diagnosis resolution. A diagnostic device 1 has a symbol injection part 3, which is composed of a symbol injection part for an active element 5 and a symbol injection part for a passive element 7, an occurrence probability providing part 9, an equal occurrence probability providing part 11, and a switching part 13. A per-test X-fault diagnosis flow by the diagnostic device 1 consists of a stage for collecting diagnostic information and a stage for drawing diagnostic conclusion. The layout of a deep-submicron LSI circuit usually needs to involve multiple layers, which means that vias are extensively used. Since via information is utilized by the symbol injection part for a passive element 7, it becomes possible to locate defects to the via level, greatly improving the diagnostic resolution.

Abstract: A method and system to automate scan synthesis at register-transfer level (RTL). The method and system will produce scan HDL code modeled at RTL for an integrated circuit modeled at RTL. The method and system comprise computer-implemented steps of performing RTL testability analysis, clock-domain minimization, scan selection, test point selection, scan repair and test point insertion, scan replacement and scan stitching, scan extraction, interactive scan debug, interactive scan repair, and flush/random test bench generation. In addition, the present invention further comprises a method and system for hierarchical scan synthesis by performing scan synthesis module-by-module and then stitching these scanned modules together at top-level. The present invention further comprises integrating and verifying the scan HDL code with other design-for-test (DFT) HDL code, including boundary-scan and logic BIST (built-in self-test).

Abstract: A method and apparatus for providing ordered capture clocks to detect or locate faults within N clock domains and faults crossing any two clock domains in a scan-based integrated circuit or circuit assembly in self-test or scan-test mode, where N>1 and each domain has a plurality of scan cells. The method and apparatus will apply an ordered sequence of capture clocks to all scan cells within N clock domains where one or more capture clocks must contain one or more shift clock pulses during the capture operation. A computer-aided design (CAD) method is further developed to realize the method and synthesize the apparatus. In order to further improve the circuit's fault coverage, a CAD method and apparatus are further developed to minimize the memory usage and generate scan patterns for full-scan and feed-forward partial-scan designs containing transparent storage cells, asynchronous set/reset signals, tri-state busses, and low-power gated clocks.

Abstract: The provided are a don't-care-bit identification method and program for identifying don't-care-bits from the first and the second input vectors in an input-vector pair while keeping the sensitization status of paths, in a combinational circuit, sensitized by applying the first and the second input vectors in serial to input lines of combinational circuit. The method identifies an unspecified bit from the first and the second input vectors V1 and V2 composed of logic values 0 and 1, which are applied to the combinational portion in a sequential circuit or to an independent combinational circuit. The method includes an identification step for identifying an unspecified bit from the first and the second input vectors, while keeping sensitization status of a part of or all of the paths, sensitized by applying the first and the second input vectors.

Abstract: A method and apparatus for testing or diagnosing faults in a scan-based integrated circuit using a unified self-test and scan-test technique. The method and apparatus comprises using a unified test controller to ease prototype debug and production test. The unified test controller further comprises using a capture clock generator and a plurality of domain clock generators each embedded in a clock domain to perform self-test or scan-test. The capture clocks generated by the capture clock generator are used to guide at-speed or reduced-speed self-test (or scan-test) within each clock domain. The frequency of these capture clocks can be totally unrelated to those of system clocks controlling the clock domains. This unified approach allows designers to test or diagnose stuck-type and non-stuck-type faults with a low-cost DFT (design-for-test) tester or a low-cost DFT debugger. A computer-aided design (CAD) method is further developed to realize the method and synthesize the apparatus.

Abstract: A method and apparatus for compacting test responses containing unknown values in a scan-based integrated circuit. The proposed X-driven compactor comprises a chain-switching matrix block and a space compaction logic block. The chain-switching matrix block switches the internal scan chain outputs before feeding them to the space compaction logic block for compaction so as to minimize X-induced masking and error masking. The X-driven compactor further selectively includes a finite-memory compaction logic block to further compact the outputs of the space compaction logic block.

Abstract: A method and apparatus for providing ordered capture clocks to detect or locate faults within N clock domains and faults crossing any two clock domains in an integrated circuit or circuit assembly in self-test or scan-test mode, where N>1 and each domain has a plurality of scan cells. The method and apparatus allows generating and loading N pseudorandom or predetermined stimuli to all the scan cells within the N clock domains in the integrated circuit or circuit assembly during the shift operation, applying an ordered sequence of capture clocks to all the scan cells within the N clock domains during the capture operation, compacting or comparing N output responses of all the scan cells for analysis during the compact/compare operation, and repeating the above process until a predetermined limiting criteria is reached. A computer-aided design (CAD) system is further developed to realize the method and synthesize the apparatus.

Abstract: The provided are logic value determination method and program for identifying unspecified bits and determining their logic values shortly. The method enables to control the total number of logic value differences between corresponding input and output lines of combinational circuit. The method includes the first step for determining, when output has a logic value and input has an unspecified value, that the unspecified bit has the logic value of output, the second step for determining, when output has an unspecified value and input has a logic value, the logic value of the unspecified bit by justification, and the third step for calculating, when input and output both have unspecified values, probabilities of output to have 0 and 1, and determining the logic value of the unspecified bit based on the difference between the probabilities. The third step is repeated until the total number reaches a target value.

Abstract: A method and apparatus for testing or diagnosing faults in a scan-based integrated circuit using a unified self-test and scan-test technique. The method and apparatus comprises using a unified test controller to ease prototype debug and production test. The unified test controller further comprises using a capture clock generator and a plurality of domain clock generators each embedded in a clock domain to perform self-test or scan-test. The capture clocks generated by the capture clock generator are used to guide at-speed or reduced-speed self-test (or scan-test) within each clock domain. The frequency of these capture clocks can be totally unrelated to those of system clocks controlling the clock domains. This unified approach allows designers to test or diagnose stuck-type and non-stuck-type faults with a low-cost DFT (design-for-test) tester or a low-cost DFT debugger. A computer-aided design (CAD) method is further developed to realize the method and synthesize the apparatus.

Abstract: The X-type of each bit permutation is determined (step 301). When there are X-types except for X-type 1, i.e., X-type with no don't-care bits, total capture state transition numbers TECTA1 and TECTA2 for capture clock pulses C1 and C2 are calculated (step 303). As a result, when TECTA1>TECTA2, an X-type is selected for the capture clock pulse C1 and a first X-filling processing is performed (see step 305). On the other hand, when TECTA1?TECTA2, an X-type is selected for the capture clock pulse C2 and a second X-filling processing is performed (step 306).

Abstract: A method and apparatus for selectively masking off unknown (‘x’) captured scan data in first selected scan cells 220 from propagating through the scan chains 221 for test, debug, diagnosis, and yield improvement of a scan-based integrated circuit 207 in a selected scan-test mode 232 or selected self-test mode. The scan-based integrated circuit 207 contains a plurality of scan chains 221, a plurality of pattern generators 208, a plurality of pattern compactors 213, with each scan chain 221 comprising multiple scan cells 220, 222 coupled in series. The method and apparatus further includes an output-mask controller 211 and an output-mask network 212 embedded on the scan data input path of second selected scan cells 222, or a set/reset controller controlling selected set/reset inputs of second selected scan cells. A synthesis method is also proposed for synthesizing the output-mask controller 211 and the set/reset controller.

Abstract: A broadcaster, system, and method for reducing test data volume and test application time in an ATE (automatic test equipment) in a scan-based integrated circuit. The scan-based integrated circuit contains multiple scan chains, each scan chain comprising multiple scan cells coupled in series. The broadcaster is a combinational logic network coupled to an optional virtual scan controller and an optional scan connector. The virtual scan controller controls the operation of the broadcaster. The system transmits virtual scan patterns stored in the ATE and generates broadcast scan patterns through the broadcaster for testing manufacturing faults in the scan-based integrated circuit. The number of scan chains that can be supported by the ATE is significantly increased. Methods are further proposed to reorder scan cells in selected scan chains, to generate the broadcast scan patterns and virtual scan patterns, and to synthesize the broadcaster and a compactor in the scan-based integrated circuit.