A Low Power Pseudo-Random BIST Technique

Peak power consumption during testing is an important concern. For scan designs, a high level of switching activity is created in the circuit during scan shifts, which increases power consumption considerably. In this paper we propose a pseudo-random BIST scheme for scan designs, which reduces the peak power consumption as well as the average power consumption as measured by the switching activity in the circuit. The method reduces the switching activity in the scan chains and the activity in the circuit under test by limiting the scan shifts to a portion of the scan chain structure using scan chain disable. Experimental results on various benchmark circuits demonstrate that the technique reduces the switching activity caused by scan shifts.     

内建自测试的测试生成方法研究

内建自测试（BIST）方法是目前可测试性设计（DFT）中应用前景最好的一种方法,其中测试生成是关系BIST性能好坏的一个重要方面。测试生成的目的在于生成尽可能少的测试向量并用以获得足够高的故障覆盖率,同时使得用于测试的硬件电路面积开销尽可能低、测试时间尽可能短。内建自测试的测试生成方法有多种,文中即对这些方法进行了简单介绍和对比研究,分析了各自的优缺点,并在此基础上探讨了BIST面临的主要问题及发展方向。     

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.     

一种基于受控LFSR的内建自测试结构及其测试矢量生成

本文提出了一种基于受控线性反馈移位寄存器（LFSR）进行内建自测试的结构及其测试矢量生成方法。使用受控LFSR可以跳过伪随机测试序列中对故障覆盖率没有贡献的测试矢量，众而达到减少测试矢量长度，缩短测试时间的目的。     

Test Cycle Count Reduction in a Parallel Scan BIST Environment

This paper describes a novel method that can be used to reduce test cycle count in a parallel access scan based Built-In-Self-Test (BIST) environment. An algorithm that allows the efficient application of deterministically generated patterns is proposed. This approach allows BIST fault coverage to be increased using deterministic vectors, while minimizing the cost, in terms of test cycles, of applying the vectors.     

BIST for network on chip communication infrastructure based on combination of extended IEEE 1149.1 and IEEE 1500 standards

In this paper we propose a BIST based method to test network on chip (NOC) communication infrastructure. The proposed method utilizes an IEEE 1149.1 architecture based on BIST to at-speed test of crosstalk faults for inter-switch links as well as an IEEE 1500-compliant wrapper to test switches themselves in NOC communication infrastructure. The former architecture includes enhanced cells intended for MAF model test patterns generation and analysis test responses, and the later architecture includes: (a) a March decoder which decodes and executes March commands, which are scanned in serially from input system, on First-In-First-Out (FIFO) buffers in the switch; and (b) a scan chain which is defined to test routing logic block of the switch.To at-speed test inter-switch links one new instruction is used to control cells and TPG controller. Two new instructions, as well as, are applied to activate March decoder and to control scan activities in switch test session. These instructions are defined to fully comply with conventional IEEE 1149.1 and IEEE 1500 standards.     

On High-Quality, Low Energy Built-In Self Test Preparation at RT-Level

Test power requirements for complex components are becoming stringent. The purpose of this paper is to reuse a recently proposed RT (Register Transfer) Level test preparation methodology to drive innovative Low-Energy (LE)/Low-Power (LP) BIST solutions for digital SoC (System on a Chip) embedded cores. RTL test generation is carried out through the definition of a reduced set of partially specified input vectors (masks), leading to a high correlation between multiple detection of RTL faults and single detection of likely physical defects. The methodology is referred as masked-based BIST, or m-BIST. BIST quality is evaluated considering three attributes: test effectiveness (TE), test length (TL) and test power (TP). LE BIST sessions are defined as short test sequences leading to high values of RT-level IFMB metrics and low-level Defects Coverage (DC). The energy and power of the BIST sessions, with and without mask forcing, is computed. It is shown that, by forcing vectors with the RTL masks, short BIST sessions, with low energy and with a comparable (or smaller) average power consumption, as compared to pseudo-random test, are derived. The usefulness of the methodology is ascertained using the VeriDOS simulation environment and modules of the CMUDSP and TORCH ITC'99 benchmark circuits.     

Partial Reset Methodology and Experiments for Improving Random-Pattern Testability and BIST of Sequential Circuits

Partial reset has been shown to have significant impact on test generation for sequential circuits in a stored-pattern test application environment. In this paper, we explore the use of partial reset in fault-independent testing and built-in self-test (BIST) of non-scan sequential circuits. We select a subset of flip-flops in the circuit to be resetable to logic one or zero during the application of the test vectors. The resetting is performed with random frequency. The selection of the flip-flops and the reset polarity is based on fault-propagation analysis, which determines the impact of a selected flip-flop on fault propagation from the circuits structure. Application of partial reset as described above yields an average improvement of 15% in fault-coverage for sequential circuits resistant to random pattern testing. To further enhance testability, we also present a methodology for selecting observable test points based on propagation of switching activity. Overall, high fault coverages (about 97%) are obtained for many of the ISCAS89 benchmark circuits. Thus, partial reset BIST provides a low cost alternative for testing sequential circuits when scan design is unacceptable due to area and/or delay constraints. The routing overhead for implementing BIST is seen to be about 6%.     

动态向量调整的多扫描链测试数据压缩

 由于多扫描链测试方案能够提高测试进度,更适合大规模集成电路的测试,因此提出了一种应用于多扫描链的测试数据压缩方案.该方案引入循环移位处理模式,动态调整向量,能够保留向量中无关位,增加向量的外延,从而提高向量间的相容性和反向相容性;同时,该方案还能够采用一种有效的参考向量更替技术,进一步提高向量间的相关性,减少编码位数.另外,该方案能够利用已有的移位寄存器,减少不必要的硬件开销.实验结果表明所提方案在保持多扫描链测试优势的前提下能够进一步提高测试数据压缩率,满足确定性测试和混合内建自测试.     

全扫描设计中多扫描链的构造

本文在交迭测试体系 的基础上提出了一种多扫描链的区间构造法,对于确定的测试向量集能够显著地减少测试应用时间.该构造方法根据规定的扫描链数,通过求解线性规划问题的方法确定扫描寄存器在扫描链上的优化的分布区间,从而构造多扫描链,最后根据对多扫描链进行连线复杂度的定性分析,求得连线复杂度最低的多扫描链的最优构造.     

Design for testability and built-in self test: a review

A summary is presented of a number of design-for-testability (DFT) and built-in self-test (BIST) schemes that can be used in modern VLSI circuits. The DFT methods presented are used to increase the controllability and observability of the circuit design. Partitioning, bus architectures, test-point insertion, and scan methods are discussed. On-chip hardware for real-time test-pattern generation and data compression are investigated. Several of the DFT methods are then combined to form BIST hardware configurations. Built-in evaluation and self-test (BEST), autonomous test, scan with random inputs, built-in logic block observer (BILBO), partitioning with BEST, test-point insertion with on-chip control, and combined test-pattern generation and data compression (CTGC) are considered. An overview of each BIST scheme is offered     

Deterministic BIST with Partial Scan

An efficient deterministic BIST scheme based on partial scan chains together with a scan selection algorithm tailored for BIST is presented. The algorithm determines a minimum number of flipflops to be scannable so that the remaining circuit has a pipeline-like structure. Experiments show that scanning less flipflops may even decrease the hardware overhead for the on-chip pattern generator besides the classical advantages of partial scan such as less impact on the system performance and less hardware overhead.     

A Signature Analysis Technique for the Identification of Failing Vectors with Application to Scan-BIST*

We present a new technique for uniquely identifying a single failing vector in an interval of test vectors. This technique is applicable to combinational circuits and for scan-BIST in sequential circuits with multiple scan chains. The proposed method relies on the linearity properties of the MISR and on the use of two test sequences, which are both applied to the circuit under test. The second test sequence is derived from the first in a straightforward manner and the same test pattern source is used for both test sequences. If an interval contains only a single failing vector, the algebraic analysis is guaranteed to identify it. We also show analytically that if an interval contains two failing vectors, the probability that this case is interpreted as one failing vector is very low. We present experimental results for the ISCAS benchmark circuits to demonstrate the use of the proposed method for identifying failing test vectors.     

并行折叠计数器的BIST方案

 本文提出了一种新的基于初始状态的并行折叠计数结构,并给出了建议的多扫描链的BIST方案.与国际上同类方法相比,该方案需要更少的测试数据存储容量、更短的测试应用时间,其平均测试应用时间是同类方案的0.265%,并且能很好地适用于传统的EDA设计流程.     

Optimization of Test Power and Data Volume in BIST Scheme Based on Scan Slice Overlapping

In order to further reduce test data storage and test power of deterministic BIST based on scan slice overlapping, this paper proposes a novel optimization approach. Firstly, a san cell grouping method considering layout constraint is introduced to shorten the scan chain. Secondly, a novel scan cell ordering approach considering layout constraint is proposed to optimize the order of scan chain. Lastly, the authors propose an improved test pattern partition algorithm which selects the scan slice with the most specified bits as the first scan slice of the current overlapping block. Experimental results indicate that the proposed optimization approach significantly reduces the scan-in transitions and test data storage by 73%–93% and 60%–87%, respectively.     

适用于嵌入式五口SRAM的多频率内建自测电路

提出了一种多频率带有扫描链的 BIST方案 ,用于五口的 32× 32嵌入式 SRAM的可测性设计。分析了多口 SRAM的结构并确定其故障模型 ,在此基础上提出了一种名为“对角线移动变反法”( OMOVI)的新算法及其电路实现。与传统的“移动变反法”( MOVI)相比 ,在保证故障覆盖率前提下 ,测试图形的测试步数由原来的12 N log2 N减小为 N/ 2 +2 N log2 N( N为 SRAM的容量 )。该方案集功能测试、动态参数提取和故障分析定位于一体 ,而且具有很强的灵活性和可扩展性     

Test data compression technique for embedded cores using virtual scan chains

This paper presents a design-for-test (DFT) technique to implement a "virtual scan chain" in a core that looks (to the system integrator) like it is shorter than the real scan chain inside the core. A core with a "virtual scan chain" is fully compatible with a core with a regular scan chain in terms of both the external test interface and tester program. The I/O pins of a core with a virtual scan chain are identical to the I/O pins of a core with a regular scan chain. For the system integrator, testing a core with a virtual scan chain is identical to testing a core with a regular scan chain (no special modes, control signals, or timing sequences are needed). The only difference is that the virtual scan chain is much shorter so the size of the scan vectors and output response is smaller resulting in less test data as well as less test time (fewer scan shift cycles). The process of mapping the virtual scan vectors to real scan vectors is handled inside the core and is completely transparent to the system integrator.     

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.     

A BIST TPG for Low Power Dissipation and High Fault Coverage

This paper presents a low hardware overhead test pattern generator (TPG) for scan-based built-in self-test (BIST) that can reduce switching activity in circuits under test (CUTs) during BIST and also achieve very high fault coverage with reasonable lengths of test sequences. The proposed BIST TPG decreases transitions that occur at scan inputs during scan shift operations and hence reduces switching activity in the CUT. The proposed BIST is comprised of two TPGs: LT-RTPG and 3-weight WRBIST. Test patterns generated by the LT-RTPG detect easy-to-detect faults and test patterns generated by the 3-weight WRBIST detect faults that remain undetected after LT-RTPG patterns are applied. The proposed BIST TPG does not require modification of mission logics, which can lead to performance degradation. Experimental results for ISCAS'89 benchmark circuits demonstrate that the proposed BIST can significantly reduce switching activity during BIST while achieving 100% fault coverage for all ISCAS'89 benchmark circuits. Larger reduction in switching activity is achieved in large circuits. Experimental results also show that the proposed BIST can be implemented with low area overhead.     

Ultra-fast CAD scan chain highlighting for failure analysis assistance

Automatic test pattern generation (ATPG) and scan tests are common design for testability methods (DfT) for digital logic ICs. A prerequisite for structural logic tests is the integrity of the embedded test circuit itself, i.e. the scan flipflops that are stringed together in scan chains. If there is a failure within one of the scan chains, localization can be quite challenging. One particular problem for failure analysis engineers is the CAD navigation along the chain: in order to display the physical position of a scan chain, hundreds or even thousands of flipflops have to be cross-mapped between the design netlist and the physical layout. This task requires extensive computing and can be very time-consuming. The work described in this paper is a new data processing method that reduces the required computing time from several hours down to a few seconds.