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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.


Lenox, Joseph Daniel 01 December 2016 (has links)
A method to perform implicit path delay fault grading on GPGPU architectures is presented. Experimentally it is shown that it is over 1200x faster than a single-core implicit path delay fault grading method previously in the literature for higher accuracy and can be shown to scale to multiple GPGPUs. A post-silicon test pattern generation strategy to maximize the efficiency of broadside tests applied to a sequential design for a limited test budget is presented. Arguments are made for this approach for detecting embedded Trojan ICs in the next-state functions of a sequential system; they are based on a model where long sequences of inputs that are applied to the system in the functional mode can detect if Trojan hardware is triggered with high probability. An efficient and scalable input generation algorithm for broadside tests is introduced and its performance on ISCAS'89 and ITC'99 benchmark circuits is evaluated. A design-for-authentication strategy is presented for the insertion of cells to efficiently partition the combinational core of a circuit to detect inserted Trojan ICs. It is shown that the approach, combined with pseudo-exhaustive test pattern generation, guarantees detection in certain circumstances.

Test Pattern Generation for Double Transition faults

Samala, Keerthana 01 August 2018 (has links)
Keerthana Samala, for the Master of Science degree in Electrical and Computer, presented on 05/11/2018, at Southern Illinois University Carbondale. TITLE: Test Pattern Generation for Double Transition Faults MAJOR PROFESSOR: Dr. Spyros Tragoudas Under double transition fault model, a fault is associated with a pair of lines and a pair of transitions on these lines. The proposed double transition fault model includes set of cases where the increased delay of a single faulty line may be too small to cause the faulty behavior of the circuit. However, when this delay propagates through another faulty line then the total delay is assumed to be beyond the specified circuit delay which may cause the circuit to fail, thus causing a double transition fault. We propose a test generation procedure for double transition faults, considering different cases of the model. For this purpose a PODEM based Automatic Test Pattern Generation Tool was modified and used. We present experimental results of this procedure for several ISCAS '85 and ISCAS'89 benchmark circuits.

High Quality Test Generation at the Register Transfer Level

Gent, Kelson Andrew 01 December 2016 (has links)
Integrated circuits, from general purpose microprocessors to application specific designs (ASICs), have become ubiquitous in modern technology. As our applications have become more complex, so too have the circuits used to drive them. Moore's law predicts that the number of transistors on a chip doubles every 18-24 months. This explosion in circuit size has also lead to significant growth in testing effort required to verify the design. In order to cope with the required effort, the testing problem must be approached from several different design levels. In particular, exploiting the Register Transfer Level for test generation allows for the use of relational information unavailable at the structural level. This dissertation demonstrates several novel methods for generating tests applicable for both structural and functional tests. These testing methods allow for significantly faster test generation for functional tests as well as providing high levels of fault coverage during structural test, typically outperforming previous state of the art methods. First, a semi-formal method for functional verification is presented. The approach utilizes a SMT-based bounded model checker in combination with an ant colony optimization based search engine to generate tests with high branch coverage. Additionally, the method is utilized to identify unreachable code paths within the RTL. Compared to previous methods, the experimental results show increased levels of coverage and improved performance. Then, an ant colony optimization algorithm is used to generate high quality tests for fault coverage. By utilizing co-simulation at the RTL and gate level, tests are generated for both levels simultaneously. This method is shown to reach previously unseen levels of fault coverage with significantly lower computational effort. Additionally, the engine was also shown to be effective for behavioral level test generation. Next, an abstraction method for functional test generation is presented utilizing program slicing and data mining. The abstraction allows us to generate high quality test vectors that navigate extremely narrow paths in the state space. The method reaches previously unseen levels of coverage and is able to justify very difficult to reach control states within the circuit. Then, a new method of fault grading test vectors is introduced based on the concept of operator coverage. Operator coverage measures the behavioral coverage in each synthesizable statement in the RTL by creating a set of coverage points for each arithmetic and logical operator. The metric shows a strong relationship with fault coverage for coverage forecasting and vector comparison. Additionally, it provides significant reductions in computation time compared to other vector grading methods. Finally, the prior metric is utilized for creating a framework of automatic test pattern generation for defect coverage at the RTL. This framework provides the unique ability to automatically generate high quality test vectors for functional and defect level testing at the RTL without the need for synthesis. In summary, We present a set of tools for the analysis and test of circuits at the RTL. By leveraging information available at HDL, we can generate tests to exercise particular properties that are extremely difficult to extract at the gate level. / Ph. D.

High Quality Compact Delay Test Generation

Wang, Zheng 2010 May 1900 (has links)
Delay testing is used to detect timing defects and ensure that a circuit meets its timing specifications. The growing need for delay testing is a result of the advances in deep submicron (DSM) semiconductor technology and the increase in clock frequency. Small delay defects that previously were benign now produce delay faults, due to reduced timing margins. This research focuses on the development of new test methods for small delay defects, within the limits of affordable test generation cost and pattern count. First, a new dynamic compaction algorithm has been proposed to generate compacted test sets for K longest paths per gate (KLPG) in combinational circuits or scan-based sequential circuits. This algorithm uses a greedy approach to compact paths with non-conflicting necessary assignments together during test generation. Second, to make this dynamic compaction approach practical for industrial use, a recursive learning algorithm has been implemented to identify more necessary assignments for each path, so that the path-to-test-pattern matching using necessary assignments is more accurate. Third, a realistic low cost fault coverage metric targeting both global and local delay faults has been developed. The metric suggests the test strategy of generating a different number of longest paths for each line in the circuit while maintaining high fault coverage. The number of paths and type of test depends on the timing slack of the paths under this metric. Experimental results for ISCAS89 benchmark circuits and three industry circuits show that the pattern count of KLPG can be significantly reduced using the proposed methods. The pattern count is comparable to that of transition fault test, while achieving higher test quality. Finally, the proposed ATPG methodology has been applied to an industrial quad-core microprocessor. FMAX testing has been done on many devices and silicon data has shown the benefit of KLPG test.

Path Delay Test Through Memory Arrays

Pokharel, Punj 16 December 2013 (has links)
Memory arrays cannot be as easily tested as other storage elements in a chip. Most of the flip-flops (FFs) in a chip can be replaced by scan cells in scan-based design. However, the bits in memory arrays cannot be replaced by scan cells, due to the area cost and the timing-critical nature of many of the paths into and out of memories. Thus, bits in a memory array can be considered non-scan storage elements. Test methods such as memory built-in self-test (MBIST), functional test, and macro test are used to test memory arrays. However, these tests aren’t sufficient to test the paths through the memory arrays. During structural (scan) test generation, memory arrays are treated as “black boxes” or memory arrays are bypassed to a known value. Black boxes decrease coverage loss while bypassing increases chip area and delay. Path delay test through memory arrays is proposed using pseudo functional test (PFT) with K Longest Paths Per Gate (KLPG). In this technique, any longest path that is captured into a non-scan cell (including a memory cell) is propagated to a scan cell. The propagation of the captured value from non-scan cell to scan cell occurs during low-speed clock cycles. In this work, we assume that only one extra coda cycle is sufficient to propagate the captured value to a scan cell. This is true if the output of the memory feeds combinational logic that in turn feeds scan cells. When we want to launch a transition from a memory output, different values are written into different address locations and the address is toggled between the locations. The ATPG writes the different values into the memory cells during the preamble cycles. In the case of launching a transition out of a non-scan cell, the cell must be written with an initial value during the preamble cycles, and the next value set on the non-scan cell input. Thus, it is possible to capture and launch transitions into and from memory and non-scan cells and thus test the path delay of the longest paths into and out of memory and non-scan cells.

ATPG based Preimage Computation: Efficient Search Space Pruning using ZBDD

Chandrasekar, Kameshwar 06 August 2003 (has links)
Preimage Computation is a fundamental step in Formal Verification of VLSI designs. Conventional OBDD-based methods for Formal Verification suffer from spatial explosion, since large designs can blow up in terms of memory. On the other hand, SAT/ATPG based methods are less demanding on memory. But the run-time can be huge for these methods, since they must explore an exponential search space. In order to reduce this temporal explosion of SAT/ATPG based methods, efficient learning techniques are needed. Conventional ATPG aims at computing a single solution for its objective. In preimage computation, we must enumerate all solutions for the target state during the search. Similar sub-problems often occur during preimage computation that can be identified by the internal state of the circuit. Therefore, it is highly desirable to learn from these search-states and avoid repeated search of identical solution/conflict subspaces, for better performance. In this thesis, we present a new ZBDD based method to compactly store and efficiently search previously explored search-states. We learn from these search-states and avoid repeating subsets and supersets of previously encountered search spaces. Both solution and conflict subspaces are pruned based on simple set operations using ZBDDs. We integrate our techniques into a PODEM based ATPG engine and demonstrate their efficiency on ISCAS '89 benchmark circuits. Experimental results show that upto 90% of the search-space is pruned due to the proposed techniques and we are able to compute preimages for target states where a state-of-the-art technique fails. / Master of Science

ATPG and DFT Algorithms for Delay Fault Testing

Liu, Xiao 03 August 2004 (has links)
With ever shrinking geometries, growing metal density and increasing clock rate on chips, delay testing is becoming a necessity in industry to maintain test quality for speed-related failures. The purpose of delay testing is to verify that the circuit operates correctly at the rated speed. However, functional tests for delay defects are usually unacceptable for large scale designs due to the prohibitive cost of functional test patterns and the difficulty in achieving very high fault coverage. Scan-based delay testing, which could ensure a high delay fault coverage at reasonable development cost, provides a good alternative to the at-speed functional test. This dissertation addresses several key challenges in scan-based delay testing and develops efficient Automatic Test Pattern Generation (ATPG) and Design-for-testability (DFT) algorithms for delay testing. In the dissertation, two algorithms are first proposed for computing and applying transition test patterns using stuck-at test vectors, thus avoiding the need for a transition fault test generator. The experimental results show that we can improve both test data volume and test application time by 46.5% over a commercial transition ATPG tool. Secondly, we propose a hybrid scan-based delay testing technique for compact and high fault coverage test set, which combines the advantages of both the skewed-load and broadside test application methods. On an average, about 4.5% improvement in fault coverage is obtained by the hybrid approach over the broad-side approach, with very little hardware overhead. Thirdly, we propose and develop a constrained ATPG algorithm for scan-based delay testing, which addresses the overtesting problem due to the possible detection of functionally untestable faults in scan-based testing. The experimental results show that our method efficiently generates a test set for functionally testable transition faults and reduces the yield loss due to overtesting of functionally untestable transition faults. Finally, a new approach on identifying functionally untestable transition faults in non-scan sequential circuits is presented. We formulate a new dominance relationship for transition faults and use it to help identify more untestable transition faults on top of a fault-independent method based on static implications. The experimental results for ISCAS89 sequential benchmark circuits show that our approach can identify many more functionally untestable transition faults than previously reported. / Ph. D.

Static Learning for Problems in VLSI Test and Verification

Syal, Manan 01 July 2005 (has links)
Static learning in the form of logic implications captures Boolean relationships between various gates in a circuit. In the past, logic implications have been applied in several areas of electronic design automation (EDA) including: test-pattern-generation, logic and fault simulation, fault diagnosis, logic optimization, etc. While logic implications have assisted in solving several EDA problems, their usefulness has not been fully explored. We believe that logic implications have not been carefully analyzed in the past, and this lack of thorough investigation has limited their applicability in solving hard EDA problems. In this dissertation, we offer deeper insights into the Boolean relationships exhibited in a circuit, and present techniques to extract their full potential in solving two hard problems in test and verification: (1) Efficient identification of sequentially untestable stuck-at faults, and (2) Equivalence checking of sequential circuits. Additionally, for the dissertation, we define a new concept called multi-cycle path delay faults (M-pdf) for latch based designs with multiple clock domains, and propose an implications-based methodology for the identification of untestable M-pdfs for such designs. One of the main bottlenecks in the efficiency of test-pattern-generation (TPG) is the presence of untestable faults in a design. State-of-the-art automatic test pattern generators (ATPG) spend a lot of effort (in both time and memory) targeting untestable faults before aborting on such faults, or, eventually identifying these faults as untestable (if given enough computational resources). In either case, TPG is considerably slowed down by the presence of untestable faults. Thus, efficient methods to identify untestable faults are desired. In this dissertation, we discuss a number of solutions that we have developed for the purpose of untestable fault identification. The techniques that we propose are fault-independent and explore properties associated with logic implications to derive conclusions about untestable faults. Experimental results for benchmark circuits show that our techniques achieve a significant increase in the number of untestable faults identified, at low memory and computational overhead. The second related problem that we address in this proposal is that of determining the equivalence of sequential circuits. During the design phase, hardware goes through several stages of optimizations (for area, speed, power, etc). Determining the functional correctness of the design after each optimization step by means of exhaustive simulation can be prohibitively expensive. An alternative to prove functional correctness of the optimized design is to determine the design's functional equivalence w.r.t. some golden model which is known to be functionally correct. Efficient techniques to perform this process, known as equivalence checking, have been investigated in the research community. However, equivalence checking of sequential circuits still remains a challenging problem. In an attempt to solve this problem, we propose a Boolean SAT (satisfiability) based framework that utilizes logic implications for the purpose of sequential equivalence checking. Finally, we define a new concept called multi-cycle path-delay faults (M-pdfs). Traditionally, path delay faults have been analyzed for flip-flop based designs over the boundary of a single clock cycle. However, path delay faults may span multiple clock cycles, and a technique is desired to model and analyze such path delay faults. This is especially essential for latch based designs with multiple clock domains, because the problem of identifying untestable faults is more complex in such design environments. In this dissertation, we propose a three-step methodology to identify untestable M-pdfs in latch-based designs with multiple clocks using logic implications. / Ph. D.

Hardware Emulation of Sequential ATPG-Based Bounded Model Checking

Ford, Gregory Fick 21 February 2014 (has links)
No description available.

Static Analysis to improve RTL Verification

Agrawal, Akash 06 March 2017 (has links)
Integrated circuits have traveled a long way from being a general purpose microprocessor to an application specific circuit. It has become an integral part of the modern era of technology that we live in. As the applications and their complexities are increasing rapidly every day, so are the sizes of these circuits. With the increase in the design size, the associated testing effort to verify these designs is also increased. The goal of this thesis is to leverage some of the static analysis techniques to reduce the effort of testing and verification at the register transfer level. Studying a design at register transfer level gives exposure to the relational information for the design which is inaccessible at the structural level. In this thesis, we present a way to generate a Data Dependency Graph and a Control Flow Graph out of a register transfer level description of a circuit description. Next, the generated graphs are used to perform relation mining to improve the test generation process in terms of speed, branch coverage and number of test vectors generated. The generated control flow graph gives valuable information about the flow of information through the circuit design. We are using this information to create a framework to improve the branch reachability analysis mainly in terms of the speed. We show the efficiency of our methods by running them through a suite of ITC'99 benchmark circuits. / Master of Science

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