An implicitly testable boundary scan TAP controller

The design of a test access port controller conforming to the boundary scan standard is described, which is implicitly tested while it is working. It is based on a novel self-test technique also applicable to other controller designs. This technique uses a signature register as state register, such that no reconfiguration of that register is necessary during self-test. This way the test of the test access port can be efficiently incorporated into the system self-test. No additional I/O pins beyond those of the boundary scan standard are necessary, neither does the test program have to be changed to incorporate the test of the controller. The solution only requires moderate hardware overheads, nevertheless it guarantees a high fault coverage.     

An IEEE 1149.1 Compliant Test Control Architecture

This paper deals with a design methodology and associated architecture to support the control of on-chip DFT and BIST hardware. The work is general in that it supports numerous test methods, such as partial and full scan, multiple and reconfigurable scan chains, and both test per clock BIST and scan BIST. The results presented here are compatible with the IEEE 1149.1 boundary scan architecture. The work is based on a hierarchical control methodology that includes systems, PCBs and MCMs. Various options for assigning control functions to be on-chip or off-chip are described. A new, partially distributed test control architecture is introduced that includes an internal test bus and distributed local controllers. There are three main modes of control of test resources, namely local static control, dynamic control and global static control. We show how the control mechanism can be implemented together with the IEEE 1149.1 test protocol. The synthesis of the on-chip test control hardware has been automated in a system called CONSYST.     

Integration of partial scan and built-in self-test

Partial-Scan based Built-In Self-Test (PSBIST) is a versatile Design for Testability (DFT) scheme, which employs pseudo-random BIST at all levels of test to achieve fault coverages greater than 98% on average, and supports deterministic partial scan at the IC level to achieve nearly 100% fault coverage. PSBIST builds its BIST capability on top a partial scan structure by adding a test pattern generator, an output data compactor, and a PSBIST controller in a way similar to that of deriving a full scan BIST from a full scan structure. However, to make the scheme effective, there is a minimum requirement regarding which flip-flops in the circuit should be replaced by scan flip-flops and/or initialization flip-flops. In addition, test arents are usually added to boost the fault coverage to the range of 95 to 100 percent. These test points are selected based on a novel probabilistic testability measure, which can be computed extremely fast for a special class of circuits. This ciass of circuits is precisely the type of circuits that we obtain after replacing some of the flip-flops.withscan and/or initilization flip-flops. The testability measure is also used for a very useful quick estimation of the fault coverage right after the selection of sean flip-flops, even before the circuit is modified to incorporate PSBIST capability. While PSBIST provides all the benefits of BIST, it incurs lower area overhead and performance degradation than full scan. The area overhead is further reduced when the boundary scan cells are reconfigured for BIST usage.     

An introduction to the boundary scan standard: ANSI/IEEE Std 1149.1

ANSI/IEEE Std 1149.1 defines a standard implementation of boundary scan that, it is hoped, will be built into many catalog and application-specific integrated circuits. The standard was developed as a solution to two continuing trends that are having a significant, adverse, impact on the task of testing loaded printed wiring boards: increasing chip complexity and greater miniaturization. The former increases the difficulty of test generation, while the latter impedes access for the bed-of-nails and hand-held probes on which many established test techniques depend.This tutorial provides a guide to the principal features defined by the standard and to their operation. It is intended as a prelude to the standard itself, not as a substitute for it. In particular, it is recommended that readers who intend to implement integrated circuits, design tools, or test systems that support the standard read the standard document before doing so.     

一款百万门缀SOC芯片的可测性设到

本文介绍了一款基于65nm工艺的数字处理芯片的可测性设计,采用了边界扫描测试,存储器内建自测试和内部扫描测试技术。这些测试技术的使用为该芯片提供了方便可靠的测试方案,实验结果表明该设计的测试覆盖率符合工程应用要求。     

边界扫描测试结构完备性诊断策略

边界扫描结构完备性测试是在其他任何测试之前建议首先进行的测试操作，以确保边界扫描结构能正常工作。本文在分析了边界扫描结构故障类型与测试原理之后提出了一种完备性诊断策略，并给出了具体实现过程。     

An Efficient Deterministic Test Pattern Generator for Scan-Based BIST Environment

To obtain satisfactory fault coverage for testing a logic circuit, linear feedback shift registers (LFSRs) have been used to generate not only the pseudorandom, but also the deterministic patterns in the scan-based built-in self-test environment. However, like other scan-based methods, the LFSR based pattern generation schemes take a long test application time to feed deterministic patterns from the LFSR into a scan chain. In this paper we derive a general relationship between the bits in the scan chain and the states of the LFSR and show that any bit to be generated by an LFSR in any future clock cycle can be pre-generated by a linear function of the current LFSR state. With this relationship, we can divide a scan chain into multiple sub-chains and use one LFSR-based multiple sequence generator to simultaneously generate all the subsequences required by the sub-chains, hence can greatly reduce the test application time for deterministic patterns. Moreover, due to the scan time reduction, test power wasted during the scan operation can also be significantly reduced.     

A language for describing boundary scan devices

Boundary scan (IEEE Standard 1149.1-1990) technology is beginning to be embraced in chip and board designs. One key need is a way to simply and effectively describe the feature set of a boundary scan compliant device in a manner both user friendly and suitable for software to utilize. A language subset of VHDL is proposed here for this purpose. As with any new standard, the industry is learning how to apply its rules and mistakes will occur. A derivative effect of the language proposed here is that if a device is not describable by the language, then that device does not comply with the 1149.1 standard. While the converse is not true, the language still allows a syntactic check for compliance as well as a number of semantic checks.     

BIST TPG for Combinational Cluster Interconnect Testing at Board Level

A novel built-in self-test (BIST) architecture and a test pattern generator (TPG) design methodology to program this architecture are presented for inter-IC interconnects among combinational non-boundary scan ICs (often called cluster-ICs) via IEEE 1149.1 boundary scan architecture (BSA). Due to the expense and complexity of BSA circuitry, cluster-ICs are still widely used in modern circuit boards. Since combinational logic and 3-state cluster nets exist within cluster interconnect, in order to test all detectable faults in inter-IC nets that include cluster-ICs, newly identified TPG requirements are used to guarantee fault coverage during the design of proposed BIST architecture. This architecture contains a two-level C-TPG that generates constrained pseudo-random patterns for boundary scan cells (BSCs) of cluster control cones, a D-TPG that generates patterns for BSCs of cluster data cones, and a look-up table which is programmed to select, for each BSC, a specific C-TPG or D-TPG stage whose content is shifted into that BSC. This test architecture provides a true BIST solution for cluster testing. The proposed methodology generates TPGs that (i) guarantee the avoidance of multi-driver conflicts when testing via BSA, (ii) guarantee the detection of all testable interconnect faults, (iii) have low area overheads, and (iv) have short test lengths.     

ATPG and diagnostics for boards implementing boundary scan

The emergence of the IEEE 1149.1 boundary scan standard facilitates structured approaches for board partitioning, allowing test generation and execution on localized logic clusters. This article discusses a study conducted on 1149.1 board designs to examine issues associated with board-level Automatic Test-Pattern Generation (ATPG) and diagnostics.     

IEEE standard 1149.1-1990 on boundary scan: History,literature survey,and current status

From humble beginnings, boundary scan has emerged as a major topic in the area of design-for-test applied to electronic devices, boards, and systems. This article reviews the literature in the field, and outlines the historical development of the new IEEE standard 1149.1–1990.Formerly with Philips CFT Automation, Eindhoven, NL.     

High-Level Test Synthesis for Behavioral and Structural Designs

High-Level Test Synthesis (HLTS), a term introduced in recent years, promises automatic enhancement of testability of a circuit. In this paper we will show how HLTS can achieve higher testability for BIST-oriented test methodologies. Our results show considering testability during high-level synthesis, better testability can be obtained when compared to DFT at low level. Transformation for testability, which allows behavioral modification for testability, is a very powerful HLTS technique.     

HIST: A hierarchical self test methodology for chips,boards, and systems

This article presents the HIST approach, which allows the automated insertion of self test hardware into hierarchically designed circuits and systems to implement the RUNBIST instruction of the IEEE 1149.1 standard. To achieve an optimal and throughout self testable system, the inherent design hierarchy is fully exploited. All chips and boards are provided with appropriate test controllers at each hierarchy level. The approach is able to detect all those faults, which are in the scope of the underlying self test algorithms. In this paper the hierarchical test architecture, the test controllers as well as all necessary synthesis procedures are presented. Finally a successful application of the HIST approach to a cryptography processor is described.     

An optimal scheduling algorithm for testing interconnect using boundary scan

Systems will soon be built with ICs that conform with the IEEE 1149.1 boundary scan architecture. Due to the hierarchical nature of such systems, they may contain many boundary scan chains. These chains can be used to test the system, subsystem, and board interconnect. To reduce test time, the application of test vectors to these scan chains must be carefully scheduled. This article deals with problems related to finding an optimal schedule for testing interconnect. This problem is modeled using a directed graph. The following results are obtained: (1) upper and lower bounds on interconnect test time; (2) necessary and sufficient conditions for obtaining an optimal schedule when the graph is acyclic; (3) sufficient condition for obtaining an optimal schedule when the graph is cyclic; and (4) an algorithm for constructing an optimal schedule for any graph.This work was supported by Defense Advanced Research Projects Agency and monitored by the Office of Naval Research under contract No. N00014-87-K-0861. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the Defense Advanced Research Projects Agency or the U.S. Government.     

Reducing test-data volume and test-power simultaneously in LFSR reseeding-based compression environment

This paper presents a new test scheme based on scan block encoding in a linear feedback shift register (LFSR) reseeding-based compression environment.Meanwhile,our paper also introduces a novel algorithm of scan-block clustering.The main contribution of this paper is a flexible test-application framework that achieves significant reductions in switching activity during scan shift and the number of specified bits that need to be generated via LFSR reseeding.Thus,it can significantly reduce the test power and test data volume.Experimental results using Mintest test set on the larger ISCAS’89 benchmarks show that the proposed method reduces the switching activity significantly by 72%-94%and provides a best possible test compression of 74%-94%with little hardware overhead.     

Generating a family of testable designs using the BILBO methodology

There are usually many different ways to make a digital circuit testable using the BILBO methodology. Each solution can have different values of test time and area overhead. A design system based on the BILBO methodology has been developed that can efficiently explore the testable design space to generate a family of designs ranging from the minimal test time design to the minimal area overhead design. A designer can select an appropriate design based on trade-offs between test time and area overhead. The branch and bound technique is employed during the exploring process to prune the design space. This significantly reduces the execution time of this process. To effectively bound the exploring process, a very efficient test scheduler has been developed. Unlike previous approaches, this new test scheduler can process a partially testable design as well as a complete testable design. A test schedule for a design is constructed incrementally. The test scheduling procedures are presented along with experimental results that show that this test scheduler usually outperforms existing schedulers. In many cases, it generates an optimal test schedule. Experiments have been performed on several circuits generated by MABAL, a CAD synthesis tool, to demonstrate the performance and practicality of this system.This work was supported by the Defense Advanced Research Projects Agency and monitored by the Federal Bureau of Investigation under Contract No. JFBI90092. The views and conclusions considered in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the Defense Advanced Research Projects Agency or the U.S. Government.     

A new reconfigurable Test Vector Generator for built-in self-test applications

This paper proposes a new approach to designing a BIST Test Vector Generator (TVG) for random vector-resistant circuits based on reconfigurable Cellular Automata Registers (CARs). Each CAR configuration is constructed by combining rules 90 and 150 and the same approach can also be applied to the Linear Feedback Shift Register (LFSR). The TVG thus designed is able to produce 100% fault coverage with short test time at the cost of low area overhead. To achieve this objective, a new method called the Rank Order Clustering (ROC) method, is introduced in order to fix a number of inputs at certain values when generating pseudorandom vectors. It is shown that the ROC method is very simple and efficient in fixing inputs at these values in terms of complexity. Experimental results have been conducted to demonstrate the applicability of the proposed approach in terms of hardware size and test application time.     

Scalable Test Generators for High-Speed Datapath Circuits

This paper explores the design of efficient test sets and test-pattern generators for on-line BIST. The target applications are high-performance, scalable datapath circuits for which fast and complete fault coverage is required. Because of the presence of carry-lookahead, most existing BIST methods are unsuitable for these applications. High-level models are used to identify potential test sets for a small version of the circuit to be tested. Then a regular test set is extracted and a test generator TG is designed to meet the following goals: scalability, small test set size, full fault coverage, and very low hardware overhead. TG takes the form of a twisted ring counter with a small decoder array. We apply our technique to various datapath circuits including a carry-lookahead adder, an arithmetic-logic unit, and a multiplier-adder.     

基于电力线通信芯片可测性设计的研究实现

集成电路的快速发展,迫切地需要快速、高效、低成本且具有可重复性的测试方案,这也成为可测性设计的发展方向。此次设计基于一款电力线通信芯片,数字部分采用传统常用的数字模块扫描链测试和存储器内建自测试;同时利用芯片正常的通信信道,引入模拟环路测试和芯片环路内建自测试,即覆盖了所有模拟模块又保证了芯片的基本通信功能,而且最大限度地减少了对芯片整体功能布局的影响。最终使芯片良率在98%以上,达到了大规模生产的要求。此设计可以为当前数模混合通信芯片的测试提供参考。     

An Implementation Approach of the IEEE 1149.1 for the Routing Test of a VLSI Massively Parallel Architecture

This paper presents an implementation approach for the test of routers in a fine grain massively parallel architecture. First, an ad hoc test technique which diffuses test messages router by router is analyzed. Even though the technique does not add hardware, it is shown inefficient and not applicable due to practical constraints such as the limited number of pins of the chip implementing the machine. Based on a hierarchical implementation of the IEEE 1149.1 standard, two approaches are proposed and compared in terms of the area overhead, the overall test time and the flexibility in applying tests and diagnosing the routers inside the machine. The basic idea for both approaches is to construct groups of basic cells which are driven by the same test block and compare their test results after the same test vectors are applied at each cell input. The two approaches differ in the granularity of a basic cell. The choice of an implementation approach is not trivial. It is shown that each approach presents better performance than the other, that is, the approach which allows better fault coverage and less test time requires more silicon and less diagnostic possibilities compared to the second approach.