Exact probabilistic testability measures for multi-output circuits

The computation of probabilistic testability measures has become increasingly important and some methods have been proposed, although the exact solution of the problem is NP-hard. An exact analytical method for singleoutput combinational circuits is extended to deal with multi-output circuits. Such circuits are reduced to singleoutput ones by introducing a dummy gate, the X-gate, and applying to the resulting graph the analysis based on supergates.     

Testability and test generation for majority voting fault-tolerant circuits

The testability of majority voting based fault-tolerant circuits is investigated and sufficient conditions for constructing circuits that are testable for all single and multiple stuck-at faults are established. The testability conditions apply to both combinational and sequential logic circuits and result in testable majority voting based fault-tolerant circuits without additional testability circuitry. Alternatively, the testability conditions facilitate the application of structured design for testability and Built-In Self-Test techniques to fault-tolerant circuits in a systematic manner. The complexity of the fault-tolerant circuit, when compared to the original circuit can significantly increase test pattern generation time when using traditional automatic test pattern generation software. Therefore, two test pattern generation algorithms are developed for detecting all single and multiple stuck-at faults in majority voting based circuits designed to satisfy the testability conditions. The algorithms are based on hierarchical test pattern generation using test patterns for the original, non-fault-tolerant circuit and structural knowledge of the majority voting based design. Efficiency is demonstrated in terms of test pattern generation time and cardinality of the resulting set of test patterns when compared to traditional automatic test pattern generation software.     

A New Method for Testing Re-Programmable PLAs

We present a method for obtaining a minimal set of test configurations and their associated set of test patterns that completely tests re-programmable Programmable Logic Arrays (PLAs) including EEPROM, UV-EPROM, and SRAM based re-programmable PLAs typically found in Complex Programmable Logic Devices (CPLDs). The resultant set of test configurations and vectors detect all single and multiple stuck-at faults (including line and transistor faults) as well as all bridging faults in the PLA. Previously proposed test methods proposed for EEPROM based PLAs (IEEE Trans. on CAD, Vol. 13, No. 7, pp.935–939, 1994;Proc. IEEE International Symposium on Defect and Fault Tolerance in VLSI Systems, 1998, pp. 146–154) require additional test hardware as well as a large number of test configurations and vectors for complete testing. Our approach requires no modification to the PLA and only two or four test configurations, depending on the ratio of PLA product terms to inputs.     

A test generation program for sequential circuits

This article presents an automatic test pattern generation system based on both algebraic and topological techniques. Circuit partitioning, testability measures, 9-valued functions, pruning heuristics, and interactive fault simulation are employed to increase the performance of a modified version of the sequential D-Algorithm. Test generation results for someIscas'89 circuits are presented.Enrico Macii is also with Politecnico di Torino, Dip. di Automatica e Informatica, Torino, Italy 10129.     

Sequential circuit test generation using dynamic justification equivalence

Automatic test pattern generation (ATPG) for sequential circuits involves making decisions in the search decision spaces bounded by a sequential circuit. The flip-flops in the sequential circuit determine the circuit state search decision space. The inputs of the circuit define the combinational search decision space. Much work on sequential circuit ATPG acceleration focused on how to make ATPG search decisions. We propose a new technique to improve sequential circuit ATPG efficiency by focusing on not repeating previous searches. This new method is orthogonal to existing deterministic sequential circuit ATPG algorithms.A common search operation in sequential circuit ATPG is justification, which is to find an input assignment to justify a desired output assignment of a component. We have observed that implications in a circuit resulting from prior justification decisions form an unique justification decomposition. Since the connectivity of a circuit does not change during ATPG, test generation for different target faults may share identical justification decision sequences represented by identical decision spaces. Because justification decomposition represents the collective effects of prior justification decisions, it is used to identify previously-explored justification decisions. Preliminary results on the ISCAS 1989 circuits show that our test generator (SEST) using justification decompositions, on average, runs 2.4 and 4.5 times faster than Gentest and Hitec, respectively. We describe the details of justification equivalence and its application in ATPG accompanied with step-by-step examples.     

神经网络在组合电路故障模拟测试生成算法中的应用

本文在基于故障模拟的测试生成算法基础上,提出了一种初始测试矢量的生成方法,即采用神经元网络模型来生成初始矢量,既避免了随机生成初始矢量的盲目性,又避免了确定性算法使用回溯所带来的大运算量。试验结果证明这种方法是有效的。     

On the generation of test patterns for multiple faults

This article presents a new method to generate test patterns for multiple stuck-at faults in combinational circuits. We assume the presence of all multiple faults of all multiplicities and we do not resort to their explicit enumeration: the target fault is a single component of possibly several multiple faults. New line and gate models are introduced to handle multiple fault effect propagation through the circuits. The method tries to generate test conditions that propagate the effect of the target fault to primary outputs. When these conditions are fulfilled, the input vector is a test for the target fault and it is guaranteed that all multiple faults of all multiplicities containing the target fault as component are also detected. The method uses similar techniques to those in FAN and SOCRATES algorithms to guide the search part of the algorithm, and includes several new heuristics to enhance the performance and fault detection capability. Experiments performed on the ISCAS'85 benchmark circuits show that test sets for multiple faults can be generated with high fault coverage and a reasonable increase in cost over test generation for single stuck-at faults.     

Novel Test Approach for Interconnect Resources in Field Programmable Gate Arrays

A novel test approach for interconnect resources(IRs)in field programmable gate arrays (FPGA)has been proposed.In the test approach,SBs (switch boxes)of IRs in FPGA has been utilized to test IRs.Furthermore,configurable logic blocks(CLBs)in FPGA have also been employed to enhance driving capability and the position of fault IR can be determined by monitoring the IRs associated SBs.As a result,IRs can be scanned maximally with minimum configuration patterns.In the experiment,an in-house developed FPGA test system based on system-on-chip(SoC)hardware/software verification technology has been applied to test XC4000E family of Xilinx.The experiment results revealed that the IRs in FPGA can be tested by 6 test patterns.     

A synthesis-based test generation and compaction algorithm for multifaults

Because of its inherent complexity, the problem of automatic test pattern generation for multiple stuck-at faults (multifaults) has been largely ignored. Recently, the observation that multifault testability is retained by algebraic factorization demonstrated that single fault (and therefore multifault) vector sets for two-level circuits could give complete multifault coverage for multilevel circuits constructed by algebraic factorization. Unfortunately, in using this method the vector set size can be much larger than what is really required to achieve multifault coverage, and the approach has some limitations in its applicability.In this article we first present a multifault test generation and compaction strategy for algebraically factored multilevel circuits, synthesized from two-level representations. We give a basic sufficiency condition for multifault testability of such networks.We next focus on the relationship between hazard-free robust path-delay-fault testability and multifault testability. We show that the former implies the latter for arbitrary multilevel circuits. This allows the use of previously developed composition rules that maintain path-delay-fault testability for the synthesis of multifault testable circuits.We identify a class of multiplexor-based networks and prove an interesting property of such networks—if the networks are fully single stuck-at fault testable, or made fully single stuck-at fault testable, they are completely multifault testable. We give a multifault test generation and compaction algorithm for such networks.We provide experimental results which indicate that a compacted multifault test set derived using the above strategies can be significantly smaller than the test set derived using previously proposed procedures. These results also indicate the substantially wider applicability of our procedures, as compared to previous techniques.     

FsmTest: Functional test generation for sequential circuits

This paper presents a new approach to test pattern generation for sequential circuits modeled as finite state machines. This approach is well suited for controller synthesis, because such devices are usually represented as explicit finite state machines. Based on a functional fault model, only a restricted set of transitions of the finite state machine (FSM) is considered for the purpose of testing. A new state discriminating sequence, referred to as EUIO is proposed. Overlapping is accomplished to reduce the test length. In most cases, test length and CPU time requirements are substantially lower compared with gate-level ATPGs. Techniques are also introduced to preserve a high fault coverage. Evaluation on MCNC benchmarks has shown the effectiveness of the test algorithm both at functional and gate levels, while achieving in most cases 100% coverage of single stuck-at faults.     

A Full Coverage Test Method for Configurable Logic Blocks in FPGA

FPGA＇s conflgurability makes it difficult for FPGA＇s manufacturers to fully test it. In this paper, a full coverage test method for FPGA＇s Conflgurable logic blocks （CLBs） is proposed, through which all basic logics of FPGA＇s every CLB can be fully tested. Innovative test circuits are designed using FPGA＇s internal resources to build Iterative logic arrays （ILAs） for Look-up tables （LUTs）, distributed random access memories, configurable registers and other logics. The programmable interconnects needed to connect CLBs in these test circuits are also repeatable, making the configuration process much easier and the test speed much faster. The test method is transplantable and independent of FPGA＇s array size, so it can be applied to the test of different FPGAs. Xilinx＇s Virtex FPGA is taken as an example to explain our method, where only 19 test configurations are needed to achieve 100% coverage for all CLBs. To evaluate the test method reliably and guide the process of test vectors generation, a fault simulator- Turbofault is used to simulate FPGA＇s test coverage.     

集成电路测试原理和向量生成方法分析

测试向量生成是集成电路测试的一个重要环节。在此从集成电路基本测试原理出发,介绍了一种ATE测试向量生成方法。通过建立器件模型和测试平台,在仿真验证后,按照ATE向量格式,直接生成ATE向量。以一种实际的双向总线驱动电路74ALVC164245为例,验证了此方法的可行性,并最终得到所需的向量文本。该方法具有较好的实用性,对进一步研究测试向量生成,也有一定的参考意义。     

Optimization-based multifrequency test generation for analog circuits

A robust test set for analog circuits has to detect faults under maximal masking effects due to variations of circuit parameters in their tolerance box. In this paper we propose an optimization based multifrequency test generation method for detecting parametric faults in linear analog circuits. Given a set of performances and a frequency range, our approach selects the test frequencies that maximize the observability on a circuit performance of a parameter deviation under the worst masking effects of normal variations of the other parameters. Experimental results are provided and validated by HSpice simulations to illustrate the proposed approach.     

An adaptive simulation framework for AMS-RF test quality

Ensuring the quality of a circuit implies ensuring the quality of test. Despite the fact that performance-based testing has been the golden standard for Analog, Mixed-Signal and RF test for decades, high-reliability markets like automotive have found that functional test leaves some potential defects undetected that can produce in-field failure. There is thus a push towards defect-oriented testing which, in turn, calls for an efficient defect simulation framework. This paper presents a statistical adaptive defect simulation based on likelihood-weighted random sampling to evaluate the quality of AMS-RF tests in terms of defect coverage and fault escape. The adaptive loop takes a decision at each new defect simulation on whether it is more efficient to assess the defect coverage or the fault escape rate of the test under evaluation, as a function of the desired targets for these two metrics. Several decision criteria are proposed and validated by simulation of a complete IC for different tests.     

面向任务成功的航空通信电子系统空地协同自主测试技术

针对航空通信电子系统测试中广泛存在的过程完备测试效率低、测试流程人为依赖、空地测试设计割裂等问题,提出了一种面向任务成功的航空通信电子系统空地协同自主测试技术。首先设计基于知识的协同自主测试架构,然后创新面向任务成功的测试逻辑生成与空地协同测试推理机技术,最后通过试验验证所提方法测试效率与自动化程度的提升。     

Test generation,design-for-testability and built-in self-test for arithmetic units based on graph labeling

In this article we discuss a test generation, design-for-testability and built-in self-test methodology for two-dimensional iterative logic arrays (ILAs) that perform arithmetic functions. Our approach is unique because a single graph labeling procedure is used to generate test vectors, implement design-for-testability as well as design the circuitry for built-in self-test. The graph labeling is based on mathematical properties of full-addition such as symmetry and self-duality. Circuit modifications are introduced by a systematic procedure based on the graph labeling, that enable them to be tested with a fixed number of tests irrespective of their size. The approach is novel as it also greatly simplifies the processes of on-chip test vector generation and response comparison that are necessary for built-in self-test. Each circuit module is tested in a pseudo-exhaustive manner with deterministic as opposed to random test sequences. This results in a comprehensive test of the circuit for which built-in self-test is designed.This research was supported by the General Electric Company and by the Semiconductor Research Corporation under contracts SRC RSCH 88-DP-108 at the University of Illinois and SRC RSCH 89-DP-142 at the University of Texas at Austin.     

A hierarchical test generation methodology for digital circuits

A new hierarchical modeling and test generation technique for digital circuits is presented. First, a high-level circuit model and a bus fault model are introduced—these generalize the classical gate-level circuit model and the single-stuck-line (SSL) fault model. Faults are represented by vectors allowing many faults to be implicitly tested in parallel. This is illustrated in detail for the special case of array circuits using a new high-level representation, called the modified pseudo-sequential model, which allows simultaneous test generation for faults on individual lines of a multiline bus. A test generation algorithm called VPODEM is then developed to generate tests for bus faults in high-level models of arbitrary combinational circuits. VPODEM reduces to standard PODEM if gate-level circuit and fault models are used. This method can be used to generate tests for general circuits in a hierarchical fashion, with both high- and low-level fault types, yielding 100 percent SSL fault coverage with significantly fewer test patterns and less test generation effort than conventional one-level approaches. Experimental results are presented for representative circuits to compare VPODEM to standard PODEM and to random test generation techniques, demonstrating the advantages of the proposed hierarchical approach.     

SOC芯片的可测试性设计与功耗优化

介绍了数字集成电路可测试性设计与测试覆盖率的概念,针对一款电力网通信芯片完成了可测试性设计,从测试的覆盖率、功耗等方面提出了优化改进方案,切实提高了芯片的测试覆盖率,缩减了测试时间和成本,降低了测试功耗,同时保证了芯片测试的可靠性,最终使芯片顺利通过量产测试。     

共形偶极子天线阵的分析与计算

本文对与有限长空心圆柱筒共形的偶极子天线阵进行了分析与计算，采用矩量法（ＭＯＭ），并利用分块求逆求广义导纳矩阵。作为例子，求解了阵中偶极子的单元方向图和输入阻抗。