摘要:
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).
摘要:
Aspects of the invention relate to low power BIST-based testing. A low power test generator may comprise a pseudo-random pattern generator unit, a toggle control unit configured to generate toggle control data based on bit sequence data generated by the pseudo-random pattern generator unit, and a hold register unit configured to generate low power test pattern data by replacing, based on the toggle control data received from the toggle control unit, data from some or all of outputs of the pseudo-random pattern generator unit with constant values during various time periods. The low power test generator may further comprise a phase shifter configured to combine bits of the low power test pattern data for driving scan chains.
摘要:
Disclosed below are representative embodiments of methods, apparatus, and systems used to reduce power consumption during integrated circuit testing. 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”) architecture). Among the disclosed embodiments are integrated circuits having programmable test stimuli selectors, programmable scan enable circuits, programmable clock enable circuits, programmable shift enable circuits, and/or programmable reset enable circuits. Exemplary test pattern generation methods that can be used to generate test patterns for use with any of the disclosed embodiments are also disclosed.
摘要:
Disclosed herein are exemplary methods, apparatus, and systems for performing timing-aware automatic test pattern generation (ATPG) that can be used, for example, to improve the quality of a test set generated for detecting delay defects or holding time defects. In certain embodiments, timing information derived from various sources (e.g. from Standard Delay Format (SDF) files) is integrated into an ATPG tool. The timing information can be used to guide the test generator to detect the faults through certain paths (e.g., paths having a selected length, or range of lengths, such as the longest or shortest paths). To avoid propagating the faults through similar paths repeatedly, a weighted random method can be used to improve the path coverage during test generation. Experimental results show that significant test quality improvement can be achieved when applying embodiments of timing-aware ATPG to industrial designs.
摘要:
A method for compressing test patterns to be applied to scan chains in a circuit under test. The method includes generating symbolic expressions that are associated with scan cells within the scan chains. The symbolic expressions are created by assigning variables to bits on external input channels supplied to the circuit under test. Using symbolic simulation, the variables are applied to a decompressor to obtain the symbolic expressions. A test cube is created using a deterministic pattern that assigns values to the scan cells to test faults within the integrated circuit. A set of equations is formulated by equating the assigned values in the test cube to the symbolic expressions associated with the corresponding scan cell. The equations are solved to obtain the compressed test pattern.
摘要:
A method for applying test patterns to scan chains in a circuit-under-test. The method includes providing a compressed test pattern of bits; decompressing the compressed test pattern into a decompressed test pattern of bits as the compressed test pattern is being provided; and applying the decompressed test pattern to scan chains of the circuit-under-test. The actions of providing the compressed test pattern, decompressing the compressed test pattern, and applying the decompressed pattern are performed synchronously at the same or different clock rates, depending on the way in which the decompressed bits are to be generated. A circuit that performs the decompression includes a decompressor such as a linear feedbackstate machine adapted to receive a compressed test pattern of bits. The decompressor decompresses the test pattern into a decompressed test pattern of bits as the compressed test pattern is being received. The circuit further includes scan chains for testing circuit logic, the scan chains coupled to the decompressor and adapted to receive the decompressed test pattern.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.