Delay Fault Testing of Look-Up Tables in SRAM-Based FPGAs

The objective of this paper is to propose a method to test all the delay faults located in Look-Up-Tables (LUTs) of SRAM-based symmetrical FPGAs. This method is developed in a Manufacturing-Oriented Context (MOT). In the first part of the paper, the timing behavior of the LUTs and the physical defects inducing delay faults in the LUTs are analyzed. Then, the detection conditions to test such delay faults are established and requirements on test vectors are derived. Finally a test configuration scheme and its associated test sequence able to test exhaustively the delay faults in all LUTs of a symmetrical FPGA are proposed.A preliminary version of this work has been presented at the European Test Workshop 2003, in MaastrichtThis revised version was published in March 2005 with corrections to one of the last authors name and the cover date.     

Distributed BIST Architecture to Combat Delay Faults

To successfully combat delay faults there is an urgent need for a proper design for testability (DFT). The foundation of any DFT methodology rests on its scan design. This paper describes three versions of a new design of a shift register latch that lend themselves to distributed self-test and delay test. The advantages of this new SRL is faster application of test vectors, higher DC and AC fault coverages, with low performance impact. Adoption of this new DFT methodology brings us closer to the ideal target of one test-per-clock as opposed to one test-per-scan. Operation, cost, and other attributes are studied in detail. Results of adopting one of these SRLs are reported on ten pilot chips.     

一种有效的双矢量测试BIST实现方案

文章提出了一种简单有效的双矢量测试BIST。实现方案．其硬件主要由反馈网络可编程且种子可重置的LF—SR和映射逻辑两部分构成。给出了一种全新的LPSR最优种子及其反馈多项式组合求取算法，该算法具有计算简单且容易实现的特点。最后。使用这种BIST、方案实现了SoC中互联总线间串扰故障的激励检测，证明了该方案在计算量和硬件开销方面的优越性。     

Scalable Delay Fault BIST for Use with Low-Cost ATE

We present a BIST architecture based on a Multi-Input Signature Register (MISR) expanding single input vectors into sequences, which are used for testing of delay faults. Input vectors can be stored on-chip or in the ATE; in the latter case, a low speed tester can be employed though the sequences are applied at-speed to the block-under-test. The number of input vectors (and thus the area demand on-chip or ATE memory requirements) can be traded for the test application time.We propose several methods for generating input vectors, which differ in test application time, area requirements and algorithm run-time. As all of them require only a two-pattern test as input, IP cores can be handled by these methods.The block-under-test can be switched off for some amount of time between application of consecutive input vectors. We provide arguments why this approach may be the only way to meet thermal and power constraints. Furthermore, we demonstrate how the BIST scheme can use these cool-down breaks for re-configuration.     

The Coupling Model for Function and Delay Faults

We propose a high-level fault model, the coupling fault (CF) model, that aims to cover both functional and timing faults in an integrated way. The basic properties of CFs and the corresponding tests are analyzed, focusing on their relationship with other fault models and their test requirements. A test generation program COTEGE for CFs is presented. Experiments with COTEGE are described which show that (reduced) coupling test sets can efficiently cover standard stuck-at-0/1 faults in a variety of different realizations. The corresponding coupling delay tests detect all robust path delay faults in any realization of a logic function. This research was sponsored in part by the U.S. National Science Foundation under Grants No. CCR-9872066 and CCR-0073406. Joonhwan Yi received the B.S degree in electronics engineering from Yonsei University, Seoul, Korea, in 1991, and the M.S. and Ph.D degrees in electrical engineering and computer science from the University of Michigan, Ann Arbor, in 1998 and 2002, respectively. From 1991 to 1995, he was with Samsung Electronics, Semiconductor Business, Korea, where he was involved in developing application specific integrated circuit cell libraries. In 2000, he was a summer intern with Cisco, Santa Clara, CA, where he worked for path delay fault testing. Since 2003, he has been with Samsung Electronics, Telecommunication Network, Suwon, Korea, where he is working on system-on-a-chip design. His current research interests include C-level system modeling for fast hardware and software co-simulation, system-level power analysis and optimization, behavioral synthesis, and high-level testing. John P. Hayes received the B.E. degree from the National University of Ireland, Dublin, and the M.S. and Ph.D. degrees from the University of Illinois, Urbana-Champaign, all in electrical engineering. While at the University of Illinois, he participated in the design of the ILLIAC III computer. In 1970 he joined the Operations Research Group at the Shell Benelux Computing Center in The Hague, where he worked on mathematical programming and software development. From 1972 to 1982 he was a faculty member of the Departments of Electrical Engineering– Systems and Computer Science of the University of Southern California, Los Angeles. Since 1982 he has been with the Electrical Engineering and Computer Science Department of the University of Michigan, Ann Arbor, where he holds the Claude E. Shannon Chair in Engineering Science. Professor Hayes was the Founding Director of the University of Michigan's Advanced Computer Architecture Laboratory (ACAL). He has authored over 225 technical papers, several patents, and five books, including Introduction to Digital Logic Design (Addison-Wesley, 1993), and Computer Architecture and Organization, (3rd edition, McGraw-Hill, 1998). He has served as editor of various technical journals, including the Communications of the ACM, the IEEE Transactions on Parallel and Distributed Systems and the Journal of Electronic Testing. Professor Hayes is a fellow of both IEEE and ACM, and a member of Sigma Xi. He received the University of Michigan's Distinguished Faculty Achievement Award in 1999 and the Humboldt Foundation's Research Award in 2004. His current teaching and research interests are in the areas of computer-aided design, verification, and testing; VLSI circuits; fault-tolerant embedded systems; ad-hoc computer networks; and quantum computing.     

逻辑内建自测移相器的设计与优化

逻辑内建自测(Logic BIST)测试结构是今后系统芯片(SOC)设计中芯片测试的发展方向。由于LFSR(线性反馈移位寄存器)生成的伪随机序列的高相关性导致故障覆盖率达不到要求，采用移相器可以降低随机序列的空间相关性，提高Logic BIST的故障覆盖率。本文分析了移相器的数学理论并提出了移相器设计与优化算法。该算法可以得到最小时延与面积代价下的高效移相器。     

Detection of Delay Faults in Memory Address Decoders

In this paper we present an efficient test concept for detection of delay faults in memory address decoders based on the march test tactic. The proposed Transition Sequence Generator (TSG) generates an optimal transition sequence for sensitization of the delay faults in address decoders by Hayes's transformation on a reflected Gray code. It can be used for parallel Built-In Self-Testing (BIST) of high-density RAMs. We also present an efficient Design For Test (DFT) approach for immediate detection of the effects of the delay faults in the address decoders which does not change memory access time. It requires extra logic to be attached to the outputs of the address decoders. This DFT approach can be used to increase memory testability for both on-line and off-line testing of single- and multi-port RAMs.     

Trade-offs in scan path and BIST implementations for RAMs

In this article we propose efficient scan path and BIST schemes for RAMs. Tools for automatic generation of these schemes have been implemented. They reduce the design effort and thus allow the designer to select the more appropriate scheme with respect to various constraints.     

A Low-Cost BIST Architecture for Linear Histogram Testing of ADCs

This paper investigates the viability of an ADC BIST scheme for implementing the histogram test technique. An original approach is developed to extract the ADC parameters from the histogram with a minimum area overhead. In particular, it is shown that the choice of a triangle-wave input signal combined with an appropriate time decomposition technique of the test procedure permits to drastically reduce the required on-chip hardware circuitry.     

Design for Delay Testability in High-Speed Digital ICs

The cost-effective testing of high-speed digital ICs is becoming increasingly problematic. Even advanced, costly testers are not always capable of testing these ICs because of their high-speed limitations. This paper focuses on a Design for Delay Testability (DfDT) technique such that high-speed ICs can be tested using inexpensive, low-speed test systems. Also extensions for possible full BIST of delay faults are addressed.     

Incorporating I DDQ Testing with BIST for Improved Coverage: An Experimental Study

In this paper we present an experimental study on the effectivenessof incorporating at-speed I _DDQ testing with traditionalBIST for improved test coverage. The high speed I _DDQtesting is conducted using the differential built-in on-chip current sensor(BICS) that we have recently developed. Two test chips were designed andfabricated implementing a CMOS version of the 74181 ALU chip. In copies ofthis circuit we included the capability of activating 45 differentrealistic CMOS faults: inter- and intra-layer shorts andopens. We examine the fault coverage of both Boolean (voltage) testing andI _DDQ testing for these realistic faults. An interestingfinding of our study is that I _DDQ testing also detectedseveral of the open faults. Moreover, these include precisely those openfaults for which two pattern voltage tests can get invalidated because oftransient switching states. Our results show that combining both Boolean andcurrent testing does enhance test coverage in a BIST environment.     

An IEEE 1149.1-based BIST method for at-speed testing of inter-switch links in network on chip

With advance in technology and working frequency reaching gigahertz, designing and testing interconnects have become an important issue. In this paper, we proposed a BIST-based boundary scan architecture to at-speed test of crosstalk faults for inter-switch communication links in network on chip. This architecture includes enhanced cells intended for MVT model test patterns generation and analysis test responses. One new instruction is used to control cells and TPG controller in the at-speed test mode in order to fully comply with conventional IEEE 1149.1 standard.     

An Approach to Minimize the Test Configuration for the Logic Cells of the Xilinx XC4000 FPGAs Family

This paper describes an approach to minimize the number of test configurations for testing the logic cells of a RAM-based FPGA taking into account the configurability of such flexible device. The proposed approach concerns the XILINX 4000 family. On this example of FPGA, a bottom-up test technique is first used to generate test configurations for the elementary modules, then test configurations for a single logic cell, and finally test configurations for the m × m array of logic cells. In this bottom-up technique, it is shown that the key point is the minimization of the number of test configurations for a logic cell. An approach for the logic cell of the XILINX4000 family is then described to define a minimum number of test configurations knowing the test configurations of its logic modules. This approach gives only 5 test configurations for the XILINX4000 family while the previous published works concerning Boolean testing of this FPGA family gives 8 or 21 test configurations.     

Efficient March Tests for a Reduced 3-Coupling and 4-Coupling Faults in Random-Access Memories

This paper presents two new march test algorithms, MT-R3CF and MT-R4CF, for detecting reduced 3-coupling and 4-coupling faults, respectively, in n × 1 random-access memories (RAMs). To reduce the length of the tests, only the coupling faults between physically adjacent memory cells have been considered. The tests assume that the storage cells are arranged in a rectangular grid and that the mapping from logical addresses to physical cell locations is known completely. The march tests need 30n and 41n operations, respectively. In this paper any memory fault is modelled by a set of primitive memory faults called simple faults. We prove, using an Eulerian graph model, the ability of the test algorithms to detect all simple coupling faults. This paper also includes a study regarding the ability of the test MT-R3CF to detect interacting linked 3-coupling faults. This work improves the results presented in [1] where a similar model of reduced 3-coupling faults has been considered and a march test with 38n operations has been proposed. To compare these new march tests with other published tests, simulation results are presented in this paper.     

Selection of Crosstalk-Induced Faults in Enhanced Delay Test

Current design trends have shown that crosstalk issues in deep sub-micron can cause severe design validation and test problems. In this paper, we address the problem of enhanced delay test considering crosstalk-induced effects. Two types of crosstalk-induced delay fault model in related works are analyzed according to their relationship to common delay fault models. The difficulties in test generation using these fault models are shown. Based on the discussion, a single precise crosstalk-induced path delay fault model, S-PCPDF model, is proposed for circuits given delay assignment. A target S-PCPDF fault gives information on a sub-path to be sensitized to generate necessary transitions coupled to a critical path. It is then convenient to enhance conventional path delay fault ATPG algorithms to implement ATPG systems for crosstalk-induced path delay faults by adding the constraints on the sub-path. We then propose two approaches to reducing the number of target S-PCPDF faults. One is based on constraints for side-inputs of paths under test. The other is based on pre-specified states during test generation for the critical path. Experimental results on ISCAS89 benchmark circuits showed that the proposed approaches can reduce the number of target faults significantly and efficiently. The CPU time for fault list reduction and test pattern generation is acceptable for circuits of reasonable sizes.Huawei Li received her B.S. degree in computer science from Xiangtan University in 1996, and M.S. and Ph.D. degrees from the Institute of Computing Technology, Chinese Academy of Sciences in 1999 and 2001 respectively. She is now an associate professor at the Institute of Computing Technology, Chinese Academy of Sciences. Her research interests include VLSI/SoC design verification and test generation, delay test, and dependable computing.Xiaowei Li received his B.Eng. and M.Eng. degrees in computer science from Hefei University of Technology (China) in 1985 and 1988 respectively, and his Ph.D. degree in computer science from the Institute of Computing Technology, Chinese Academy of Sciences in 1991. Dr. Li joined Peking University (China) as a Postdoctoral Research Associate in 1991, and was promoted to Associate Professor in 1993, all with the Department of Computer Science and Technology. From 1997 to 1998, he was a Visiting Research Fellow in the Department of Electrical and Electronic Engineering at the University of Hong Kong. In 1999 and 2000, he was a Visiting Professor in the Graduate School of Information Science, Nara Institute of Science and Technology, Japan. He Joined the Institute of Computing Technology, Chinese Academy of Sciences as a professor in 2000. At present, he is a vice-director of the laboratory of information networks. His research interests include VLSI/SoC design verification and test generation, design for testability, low-power design, dependable computing. Dr. Li received the Natural Science Award from the Chinese Academy of Sciences in 1992, the Certificate of Appreciation from IEEE Computer Society in 2001. He is a senior member of IEEE and a senior member of China Computer Federation. He is an editor of Journal of Computer Science and Technology and Journal of Computer-Aided Design & Computer Graphics (in Chinese).     

An Efficient Built‐in Self‐Test Algorithm for Neighborhood Pattern‐ and Bit‐Line‐Sensitive Faults in High‐Density Memories

As the density of memories increases, unwanted interference between cells and the coupling noise between bit‐lines become significant, requiring parallel testing. Testing high‐density memories for a high degree of fault coverage requires either a relatively large number of test vectors or a significant amount of additional test circuitry. This paper proposes a new tiling method and an efficient built‐in self‐test (BIST) algorithm for neighborhood pattern‐sensitive faults (NPSFs) and new neighborhood bit‐line sensitive faults (NBLSFs). Instead of the conventional five‐cell and nine‐cell physical neighborhood layouts to test memory cells, a four‐cell layout is utilized. This four‐cell layout needs smaller test vectors, provides easier hardware implementation, and is more appropriate for both NPSFs and NBLSFs detection. A CMOS column decoder and the parallel comparator proposed by P. Mazumder are modified to implement the test procedure. Consequently, these reduce the number of transistors used for a BIST circuit. Also, we present algorithm properties such as the capability to detect stuck‐at faults, transition faults, conventional pattern‐sensitive faults, and neighborhood bit‐line sensitive faults.     

Resynthesis of Combinational Circuits for Path Count Reduction and for Path Delay Fault Testability

Path delay fault model is the most suitable model for detectingdistributed manufacturing defects which can cause delayfaults. However, the number of paths in a modern design can beextremely large and the path delay testability of many practicaldesigns is very low. In this paper we show how to resynthesize acombinational circuit in order to reduce the total number of paths inthe circuit. Our results show that it is possible to obtain circuitswith a significant reduction in the number of paths while notincreasing area and/or delay of the longest sensitizable path in thecircuit.Research on path delay testing shows that in many circuits a largeportion of paths does not have a test that can guarantee detection ofa delay fault. The path delay testability of a circuit would increaseif the number of such paths is reduced. We show that addition of asmall number of test points into the circuit can help reducing thenumber of such paths in the given design.     

用可编程逻辑器件进行组合电路设计时的延时分析

随着高校EDA教学的不断深入,学生往往只注重设计工具、编程语言的熟练程度,而忽视了电路设计中的一些基本问题。本文详细分析了组合电路中延时错误产生的原因,并提出了三种解决方法。     

65nm工艺下基于PCI Express2.0协议的物理编码子层设计

设计了一种应用于PCIExpress2．0协议的物理编码子层,可以与物理媒介连接子层共同构成独立的物理层芯片。本文从面积与功耗方面对8b10b编解码的两种实现方法进行比较;并设计了复位控制器、头字符检测电路、时钟补偿弹性缓冲器、内建自测试等电路。全部电路在SMIC65nraCMOS工艺下综合,SS工艺角、工作频率500MHz条件下芯片面积为5500μmz,动态功耗为2．74mW。     

An Architecture for Differentiated Protection Against Single and Double Faults in GMPLS

In the context of an optical network GMPLS can be used to provide network robustness to faults through end-to-end path protection techniques. In this paper, we present a dynamic distributed model supporting five different classes of protection, including protection against single and double fault, with and without sharing of backup bandwidth. Beyond link and node failures we also consider protection against shared risk link group (SLRG) failure. In this paper, we briefly describe the protection model and the underlying algorithms for route selection and backup bandwidth sharing. After that we face the following issue: Which subset out of the five possible protection classes is convenient for an operator to support on the same network infrastructure? To answer this question it is fundamental to have a clear view of the trade-offs between the costs and the performances associated to each class. To achieve that we carried out an extensive performance analysis by means of simulations. For each protection class, we evaluated two fundamental performance metrics: the recovery probability under multiple faults, and the average per-demand resource usage. On the basis of such results, we are able to identify some basic guidelines driving the choice of the more convenient subset of protection classes to be implemented within a single network.