基于数据相关性的测试数据压缩方法

为了减少测试数据量,提出一种利用数据中大量无关位的特殊相关性进行编码压缩的方法,压缩步骤分两步,先选定参考数据,然后利用相关性将与参考数据兼容的数据块编码为"11",数据互补的数据块编码为"10",弥补了FDR码单一编码的不足.解压结构包括一个与参考数据等长的循环移位寄存器和一个有限状态机,结构简单,与Golomb码和FDR码中需要一个与测试向量等长的循环移位寄存器相比,消耗的硬件资源小.针时ISCAS-89标准电路测试向量集的压缩实验结果表明,该方法可以有效地压缩测试数据.且效果比Golomb码和FDR码更好,硬件开销更小.     

基于可配置LFSR的低功耗确定性矢量生成技术的研究

针对组合电路内建自测试过程中的功耗和故障覆盖率等问题,提出了一种能获得较高故障覆盖率的低功耗测试矢量生成方案。该方案先借助A talanta测试矢量生成工具,针对不同的被测电路生成故障覆盖率较高的测试矢量,再利用插入单跳变测试矢量的方法以及可配置线性反馈移位寄存器生成确定性测试向量的原理,获得低功耗测试矢量。通过对组合电路集ISCAS’85的实验,证实了这种测试生成方案的有效性。     

低功耗测试向量产生技术的研究

测试功耗问题是当今深亚微米芯片设计领域研究的热点,低功耗测试向量产生技术能够产生低功耗测试向量,且不需要对设计进行内在修改.文中分析了低功耗测试的重要性及现有低功耗测试向量产生方法,从外部测试、内建自测试和测试数据压缩技术三方面分析了低功耗测试向量产生技术的基本思路、研究现状及其优缺点,提出连续测试向量间的相关性是低功耗测试向量产生技术的关键问题.     

一种混合定变长虚拟块游程编码的测试数据压缩方案

 文章提出了一种混合定变长虚拟块游程编码的测试数据压缩方案,该方案将测试向量级联后分块,首先在块内找一位或最大一位表示,再对块内不能一位表示的剩下位进行游程编码,这样减少了游程编码的数据量,从而突破了传统游程编码方法受原始测试数据量的限制.对ISCAS 89部分标准电路的实验结果显示,本文提出的方案在压缩效率明显优于类似的压缩方法,如Golomb码、FDR码、VIHC码、v9C码等.     

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.     

在基于LFSR重播种的压缩环境下同时降低测试数据量和测试功耗

集成电路测试中过高的测试功耗和日益增长的测试数据量是半导体工业面临的两大问题。本文提出了一种在基于线性反馈移位寄存器重播种的压缩环境下基于扫描块的测试向量编码方案。同时,本文也介绍了一种新颖的扫描块重聚类算法。本文的主要贡献是给出了一种灵活的测试应用框架,它能够极大地减少扫描移位期间的跳变个数和经由LFSR重播种生成的确定位的数目。因此,文中方案能够极大地降低测试功耗和测试数据量。在ISCAS’89基准电路上使用Mintest测试集进行的实验表明,本文方法能够减少72%-94%的跳变,并且能获得高达74%-94%的测试压缩率。     

采用字典词条衍生模式的测试数据压缩

为了降低数字集成电路测试成本,压缩预先计算的测试集是一种有效的解决途径。该文根据索引位数远少于字典词条,以及测试数据中存在大量无关位,提出一种采用词条衍生和二级编码的字典压缩方案。该方案引入循环移位操作,确保无关位按序任意移动而不丢失,从而扩大词条衍生性能,减少非词条向量个数。另外,采用规则的两级编码可以减少码字数量和解压电路的复杂度。实验结果表明该文所提方案能够进一步提高测试数据压缩率,减少测试时间。     

一种基于编码的低硬件开销的测试数据压缩方法

提出了一种新的测试数据压缩/解压缩的算法,称为混合游程编码,它充分考虑了测试数据的压缩率、相应硬件解码电路的开销以及总的测试时间.该算法是基于变长-变长的编码方式,即把不同游程长度的字串映射成不同长度的代码字,可以得到一个很好的压缩率.同时为了进一步提高压缩率,还提出了一种不确定位填充方法和测试向量的排序算法,在编码压缩前对测试数据进行相应的预处理.另外,混合游程编码的研究过程中充分考虑到了硬件解码电路的设计,可以使硬件开销尽可能小,并减少总的测试时间.最后,ISCAS 89 benchmark电路的实验结果证明了所提算法的有效性.     

一种基于测试集分组的广义交替码

测试数据编码压缩是一类重要、经典的测试源划分（TRP）方法。本文提出了一种广义交替码,将FDR码、交替码都看作它的特例;又扩展了两步压缩方法,将原测试集划分成多组,每组采用不同的比值进行交替编码,综合了交替码与两步编码各自的优势,弥补了FDR码,交替码对某些电路测试集压缩的缺陷,得到了较好的压缩率。实验结果表明,与同类型的编码压缩方法相比,该方案具有更高的测试数据压缩率和较好的综合测试性能。     

一种低功耗BIST测试产生器方案

低功耗设计呼唤低功耗的测试策略。文章提出了一种在不损失固定型故障覆盖率的前提下降低测试功耗的内建自测试测试产生器方案，该方案在原始线性反馈移位寄存器的基础上添加简单的控制逻辑，对LFSR的输出和时钟进行调整，从而得到了准单输入跳变的测试向量集，使得待测电路的平均功耗大大降低，给出了以ISCAS'85/89部分基准电路为对象的实验结果，电路的平均测试功耗降幅在54．4％－98．0％之间，证明了该方案的有效性。     

Achieving low capture and shift power in linear decompressor-based test compression environment

Growing test data volume and excessive power dissipation are two major issues in testing of very large scale integrated (VLSI) circuits. Most previous low power techniques cannot work well with test-data compression schemes. Even if some low power methods can be applied in a test compression environment, they cannot reduce shift power and capture power simultaneously. This paper presents a new low shift-in power scan testing scheme in linear decompressor-based test compression environment. By dividing the test cubes into two kinds of blocks: non-transitional (low toggles) and transitional (with toggles) and feeding scan chains with these blocks through a novel DFT architecture, this approach can effectively reduce the quantity of transitions while scanning-in a test pattern. A low capture and shift-out power X-filling method compatible with the scan testing scheme is also proposed. The X-filling method assigns an interdependent X-bits set at each run and achieves significant power reduction. Interestingly, in the comprehensive strategy, capture power reduction agrees with shift-out power reduction to a certain extent. Experimental results on the larger ISCAS'89 and ITC'99 benchmark circuits show that the holistic strategy can reduce test power in shift cycles and capture cycles significantly under the constraint of certain compression ratio.     

LFSR Reseeding-Oriented Low-Power Test-Compression Architecture for Scan Designs

Massive test data volume and excessive test power consumption have become two strict challenges for very large scale integrated circuit testing. In BIST architecture, the unspecified bits are randomly filled by LFSR reseeding-based test compression scheme, which produces enormous switching activities during circuit testing, thereby causing high test power consumption for scan design. To solve the above thorny problem, LFSR reseeding-oriented low-power test-compression architecture is developed, and an optimized encoding algorithm is involved in conjunction with any LFSR-reseeding scheme to effectively reduce test storage and power consumption, it includes test cube-based block processing, dividing into hold partition sets and updating hold partition sets. The main contributions is to decrease logic transitions in scan chains and reduce specified bit in test cubes generated via LFSR reseeding. Experimental results demonstrate that the proposed scheme achieves a high test compression efficiency than the existing methods while significantly reduces test power consumption with acceptable area overhead for most Benchmark circuits.     

A New Scan Partition Scheme for Low‐Power Embedded Systems

A new scan partition architecture to reduce both the average and peak power dissipation during scan testing is proposed for low‐power embedded systems. In scan‐based testing, due to the extremely high switching activity during the scan shift operation, the power consumption increases considerably. In addition, the reduced correlation between consecutive test patterns may increase the power consumed during the capture cycle. In the proposed architecture, only a subset of scan cells is loaded with test stimulus and captured with test responses by freezing the remaining scan cells according to the spectrum of unspecified bits in the test cubes. To optimize the proposed process, a novel graph‐based heuristic to partition the scan chain into several segments and a technique to increase the number of don't cares in the given test set have been developed. Experimental results on large ISCAS89 benchmark circuits show that the proposed technique, compared to the traditional full scan scheme, can reduce both the average switching activities and the average peak switching activities by 92.37% and 41.21%, respectively.     

Capture-power-aware test data compression using selective encoding

Ever-increasing test data volume and excessive test power are two of the main concerns of VLSI testing. The “don’t-care” bits (also known as X-bits) in given test cube can be exploited for test data compression and/or test power reduction, and these techniques may contradict to each other because the very same X-bits are likely to be used for different optimization objectives. This paper proposes a capture-power-aware test compression scheme that is able to keep capture-power under a safe limit with low test compression ratio loss. Experimental results on benchmark circuits validate the effectiveness of the proposed solution.     

Enhancement of test data compression with multistage encoding

In this paper, we present two multistage compression techniques to reduce the test data volume in scan test applications. We have proposed two encoding schemes namely alternating frequency-directed equal-run-length (AFDER) coding and run-length based Huffman coding (RLHC). These encoding schemes together with the nine-coded compression technique enhance the test data compression ratio. In the first stage, the pre-generated test cubes with unspecified bits are encoded using the nine-coded compression scheme. Later, the proposed encoding schemes exploit the properties of compressed data to enhance the test data compression. This multistage compression is effective especially when the percentage of do not cares in a test set is very high. We also present the simple decoder architecture to decode the original data. The experimental results obtained from ISCAS'89 benchmark circuits confirm the average compression ratio of 74.2% and 77.5% with the proposed 9C-AFDER and 9C-RLHC schemes respectively.     

A New Scan Architecture for Both Low Power Testing and Test Volume Compression Under SOC Test Environment

A new scan architecture for both low power testing and test volume compression is proposed. For low power test requirements, only a subset of scan cells is loaded with test stimulus and captured with test responses by freezing the remaining scan cells according to the distribution of unspecified bits in the test cubes. In order to optimize the proposed process, a novel graph-based heuristic is proposed to partition the scan chains into several segments. For test volume reduction, a new LFSR reseeding based test compression scheme is proposed by reducing the maximum number of specified bits in the test cube set, s _max, virtually. The performance of a conventional LFSR reseeding scheme highly depends on s _max. In this paper, by using different clock phases between an LFSR and scan chains, and grouping the scan cells by a graph-based grouping heuristic, s _max could be virtually reduced. In addition, the reduced scan rippling in the proposed test compression scheme can contribute to reduce the test power consumption, while the reuse of some test results as the subsequent test stimulus in the low power testing scheme can reduce the test volume size. Experimental results on the largest ISCAS89 benchmark circuits show that the proposed technique can significantly reduce both the average switching activity and the peak switching activity, and can aggressively reduce the volume of the test data, with little area overhead, compared to the previous methods.

An Efficient Test Data Compression Technique Based on Codes

提出了一种新的测试数据压缩/解压缩的算法,称为混合游程编码,它充分考虑了测试数据的压缩率、相应硬件解码电路的开销以及总的测试时间.该算法是基于变长-变长的编码方式,即把不同游程长度的字串映射成不同长度的代码字,可以得到一个很好的压缩率.同时为了进一步提高压缩率,还提出了一种不确定位填充方法和测试向量的排序算法,在编码压缩前对测试数据进行相应的预处理.另外,混合游程编码的研究过程中充分考虑到了硬件解码电路的设计,可以使硬件开销尽可能小,并减少总的测试时间.最后,ISCAS 89 benchmark电路的实验结果证明了所提算法的有效性.