摘要:
Methods and devices for using high-speed serial links for scan testing are disclosed. The methods can work with any scheme of scan data compression or with uncompressed scan testing. The protocol and hardware to support high speed data transfer reside on both the tester and the device under test. Control data may be transferred along with scan data or be partially generated on chip. Clock signals for testing may be generated on chip as well. In various implementations, the SerDes (Serializer/Deserializer) may be shared with other applications. The Aurora Protocol may be used to transport industry standard protocols. To compensate for effects of asynchronous operation of a conventional high-speed serial link, buffers may be used. The high-speed serial interface may use a data conversion block to drive test cores.
摘要:
Methods and devices for using high-speed serial links for scan testing are disclosed. The methods can work with any scheme of scan data compression or with uncompressed scan testing. The protocol and hardware to support high speed data transfer reside on both the tester and the device under test. Control data may be transferred along with scan data or be partially generated on chip. Clock signals for testing may be generated on chip as well. In various implementations, the SerDes (Serializer/Deserializer) may be shared with other applications. The Aurora Protocol may be used to transport industry standard protocols. To compensate for effects of asynchronous operation of a conventional high-speed serial link, buffers may be used. The high-speed serial interface may use a data conversion block to drive test cores.
摘要:
Disclosed are representative embodiments of methods, apparatus, and systems for test scheduling for testing a plurality of cores in a system on circuit. Test data are encoded to derive compressed test patterns that require small numbers of core input channels. Core input/output channel requirement information for each of the compressed test patterns is determined accordingly. The compressed patterns are grouped into test pattern classes. The formation of the test pattern classes is followed by allocation circuit input and output channels and test application time slots that may comprise merging complementary test pattern classes into clusters that can work with a particular test access mechanism. The test access mechanism may be designed independent of the test data.
摘要:
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.
摘要:
Disclosed are representative embodiments of methods, apparatus, and systems for test scheduling and test access in a test compression environment. Clusters of test patterns for testing a plurality of cores in a circuit are formed based on test information that includes compressed test data, corresponding tester channel requirements and correlated cores. The formation of test pattern clusters is followed by tester channel allocation. A best-fit scheme or a balanced-fit scheme may be employed to generate channel allocation information. A test access circuit for dynamic channel allocation can be designed based on the channel allocation information.
摘要:
Disclosed are representative embodiments of methods, apparatus, and systems for test scheduling for testing a plurality of cores in a system on circuit. Test data are encoded to derive compressed test patterns that require small numbers of core input channels. Core input/output channel requirement information for each of the compressed test patterns is determined accordingly. The compressed patterns are grouped into test pattern classes. The formation of the test pattern classes is followed by allocation circuit input and output channels and test application time slots that may comprise merging complementary test pattern classes into clusters that can work with a particular test access mechanism. The test access mechanism may be designed independent of the test data.
摘要:
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.
摘要:
Method and apparatus for synthesizing high-performance linear finite state machines (LFSMs) such as linear feedback shift registers (LFSRs) or cellular automata (CA). Given a characteristic polynomial for the circuit, the method obtains an original LFSM circuit such as a type I or type II LFSR. Feedback connections within the original circuit are then determined. Subsequently, a number of transformations that shift the feedback connections can be applied in such a way that properties of the original circuit are preserved in a modified LFSM circuit. In particular, if the original circuit is represented by a primitive characteristic polynomial, the method preserves the maximum-length property of the original circuit in the modified circuit and enables the modified circuit to produce the same m-sequence as the original circuit. Through the various transformations, a modified LFSM circuit can be created that provides higher performance through shorter feedback connection lines, fewer levels of logic, and lower internal fan-out.
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 finite state 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.
摘要:
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.