一种基于轮流扫描捕获的低功耗低费用BIST方法

过高的测试功耗和过长的测试应用时间是基于伪随机内建自测试(BIST)的扫描测试所面临的两大主要问题.提出了一种基于扫描子链轮流扫描捕获的BIST方法.在提出的方法中,每条扫描链被划分成N(N>1)条子链,使用扫描链阻塞技术,同一时刻每条扫描链中只有一条扫描子链活跃,扫描子链轮流进行扫描和捕获,有效地降低了扫描移位和响应捕获期间扫描单元的翻转频率.同时,为检测抗随机故障提出了一种适用于所提出测试方法的线性反馈移位寄存器(LFSR)种子产生算法.在ISCAS89基准电路上进行的实验表明,提出的方案不但降低约(N-1)?N的平均功耗和峰值功耗,而且显著地减少随机测试的测试应用时间和LFSR重播种的种子存储量.     

Scan BIST with biased scan test signals

The conventional test-per-scan built-in self-test （BIST） scheme needs a number of shift cycles followed by one capture cycle. Fault effects received by the scan flipflops are shifted out while shifting in the next test vector like scan testing. Unlike deterministic testing, it is unnecessary to apply a complete test vector to the scan chains. A new scan-based BIST scheme is proposed by properly controlling the test signals of the scan chains. Different biased random values are assigned to the test signals of scan flip-flops in separate scan chains. Capture cycles can be inserted at any clock cycle if necessary. A new testability estimation procedure according to the proposed testing scheme is presented. A greedy procedure is proposed to select a weight for each scan chain. Experimental results show that the proposed method can improve test effectiveness of scan-based BIST greatly, and most circuits can obtain complete fault coverage or very close to complete fault coverage.     

基于组合解压缩电路的多扫描链测试方法

提出一种采用组合电路实现解压缩电路的压缩方法,只需少量的输入管脚,可以驱动大量的内部扫描链·该方法利用确定性测试向量中存在的大量的不确定位(X位),采用对测试向量进行切片划分和兼容赋值的思想,通过分析扫描切片之间的兼容关系来寻找所需的外部扫描输入管脚的最小个数·实验结果表明,它能有效地降低测试数据量·此外,通过应用所提出的解压缩电路,扫描链的条数不再受到自动测试仪的限制,因此能充分发挥多扫描链设计降低测试应用时间的优点·     

UMC-Scan Test Methodology: Exploiting the Maximum Freedom of Multicasting

Industry has used scan-based designs widely to promote test quality. However, for larger designs, the growing test data volume has significantly increased test cost because of excessively long test times and elevated tester memory and external test channel requirements. To address these problems, researchers have proposed numerous test compression architectures. In this article, we propose a flexible scan test methodology called universal multicasting scan (UMC scan). It has three major features: First, it provides a better than state-of-the-art test compression ratio using multicasting. Second, it accepts any existing test patterns and doesn't need ATPG support. Third, unlike most previous multicasting schemes that use mapping logic to partition the scan chains into hard configurations, UMC scan's compatible scan chain groups are defined by control bits, as in the segmented addressable scan (SAS) architecture. We have developed several techniques to reduce the extra control bits so that the overall test compression ratio can approach that of the ideal multicasting scheme.     

Survey of Scan Chain Diagnosis

Scan-based testing has proven to be a cost-effective method for achieving good test coverage in digital circuits. The Achilles heel in the application of scan-based testing is the integrity of the scan chains. The amount of die area consumed by scan elements, chain connections, and control circuitry varies with different designs. Typically, each scan cell in a scan chain has an index number. The cells in the chain are sequentially numbered from scan output to scan input, starting with 0. A chain pattern (sometimes called a flush pattern) is a pattern consisting of shift-in and shift-out operations without pulsing capture clocks. The purpose of chain patterns is to test scan chain integrity. A scan pattern (also known as a logic test pattern) is a pattern consisting of a shift-in operation, one or multiple capture clock cycles, and a shift-out operation. The purpose of scan patterns is to test system logic. The scan cells between the scan chain input and a scan cell's scan input terminal are called the upstream cells of that scan cell. The scan cells between the scan chain output and a scan cell's scan output terminal are called the downstream cells of that scan cell.     

一种基于扫描链阻塞技术的低费用测试方法

为进一步降低测试功耗及测试应用时间,提出一种基于扫描链阻塞技术且针对非相容测试向量的压缩方法.该方法考虑前后2个测试向量之间不相容的扫描子链,后一个测试向量可以由扫描输入移入若干位以及前一个测试向量的前若干位组合而成.实验结果表明,该方法能够有效减少测试应用时间,提升效率.     

Testing Defects in Scan Chains

Applying scan-based DFT, I_DDQ testing, or both to sequential circuits does not ensure bridging-fault detection, which depends on the resistance of the fault and circuit level parameters. With a “transparent” scan chain, however, the tester can use both methods to detect manufacturing process defects effectively-including difficult-to-detect shorts in the scan chain. The author presents a strategy for making the scan chain transparent. The test complexity of such a chain is very small, regardless of the number of flip-flops it contains     

On Test Data Compression Using Selective Don't-Care Identification

This paper proposes an effective method for reducing test data volume under multiple scan chain designs. The proposed method is based on reduction of distinct scan vectors using selective don't-care identification. Selective don't-care identification is repeatedly executed under condition that each bit of frequent scan vectors is fixed to binary values (0 or 1). Besides, a code extension technique is adopted for improving compression efficiency with keeping decompressor circuits simple in the manner that the code length for infrequent scan vectors is designed as double of that for frequent ones. The effectiveness of the proposed method is shown through experiments for ISCAS'89 and ITC'99 benchmark circuits.     

Fast and energy-frugal deterministic test through efficient compression and compaction techniques

Conversion of the flip-flops of the circuit into scan cells helps ease the test challenge; yet test application time is increased as serial shift operations are employed. Furthermore, the transitions that occur in the scan chains during these shifts reflect into significant levels of circuit switching unnecessarily, increasing the power dissipated. Judicious encoding of the correlation among the test vectors and construction of a test vector through predecessor updates helps reduce not only test application time but also scan chain transitions as well. Such an encoding scheme, which additionally reduces test data volume, can be further enhanced through appropriately ordering and padding of the test cubes given. The experimental results confirm the significant reductions in test application time, test data volume and test power achieved by the proposed compression methodology.     

使用双重种子压缩的混合模式自测试

提出了一种基于扫描混合模式的内建自测试的新颖结构，为了减少确定测试模式的存储需求，它依赖一个双重种子压缩方案，采用编码折叠计数器种子作为一个LFSR种子，压缩确定测试立方体的个数以及它的宽度．这种建议的内建自测试结构是完全相容于标准的扫描设计，简单而具有柔性，并且多个逻辑芯核可以共享．实验结果表明，这种建议的方案比先前所公布方法需要更少的测试数据存储，并且具有相同的柔性和扫描相容性。     

VirtualScan: Test Compression Technology Using Combinational Logic and One-Pass ATPG

IC testing based on a full-scan design methodology and ATPG is the most widely used test strategy today. However, rapidly growing test costs are severely challenging the applicability of scan-based testing. Both test data size and number of test cycles increase drastically as circuit size grows and feature size shrinks. For a full-scan circuit, test data volume and test cycle count are both proportional to the number of test patterns N and the longest scan chain length L. To reduce test data volume and test cycle count, we can reduce N, L, or both. Earlier proposals focused on reducing the number of test patterns N through pattern compaction. All these proposals assume a 1-to-1 scan configuration, in which the number of internal scan chains equals the number of external scan I/O ports or test channels (two ports per channel) from ATE. Some have shown that ATPG for a circuit with multiple clocks using the multicapture clocking scheme, as opposed to one-hot clocking, generates a reduced number of test patterns.     

一种多扫描链混合测试数据压缩方法

针对集成电路测试数据量大、测试应用时间长和测试结构复杂等问题,提出一种多扫描链的混合测试数据压缩方法。对于含无关位较多的测试向量,使用伪随机向量产生器生成。对于含无关位较少的向量,则直接使用自动测试设备存储。将该方法与另一种基于扫描阻塞的测试方法进行比较,理论分析和实验结果表明,该方法对数据的压缩效果优于单纯用伪随机方式的扫描阻塞测试方法。     

基于扫描的低测试功耗结构设计

在集成电路设计中,面积、功耗和可测性是3个最为重要的优化指标,测试成本正随着集成电路规模的不断增大而提高,因此在设计中加入可测性设计的考虑已成为共识,基于扫描的可测性设计方法是目前应用最广泛的方法之一,加入扫描结构可以大大提高电路系统的测试性能,但同时也会给系统的面积、性能、功耗等带来一些负面影响,提出一种考虑低功耗因素的可测性设计方法,计算数据显示,与传统扫描设计方法相比,这种方法在改善系统测试功耗方面具有突出的优势。     

扩展相容性扫描树中的测试响应压缩器设计

在扫描树测试技术中,对相容单元扫描移入相同的测试向量值可以显著地减少测试应用时间,但会使测试需要的引脚数和测试响应数据量增大.为了减少扫描树测试结构需要的引脚数以及测试响应数据量,同时克服错误位扩散带来的困难,在异或网络的基础上,提出一种适用于扫描树结构的测试响应压缩器.该压缩器由扩散抑制电路和异或网络构成,通过抑制电路消除错误位扩散给测试响应压缩带来的困难.最后,用实验数据从性能上分析了该测试响应压缩器的适用性,对于ISCAS89标准电路,最高将输出压缩74倍,且没有混叠产生.     

Testability features of the AMD-K6 microprocessor

The AMD-K6's embedded design-for-testability structures and test pattern development methodologies provide high-quality manufacturing tests. The DFT features support static voltage-level testing for wafer-sort and debug testing, application of two pattern sequences for detection of timing-related failures, scan-based BIST, and 1149.1 boundary scan     

采用循环移位和优化编码的测试压缩方法

日益增加的集成电路测试成本变得越来越难以接受,因而提出了一种简单而有效的解决方案.该方案把循环移位技术应用到测试数据压缩中,比起一般的移位技术,该方案更能有效地利用测试集中无关位.结合异或逻辑运算,所提方案累积无关位,进一步提高测试向量与其参考向量的相容性和反向相容性.在编码过程中对各种可能移位状态进行统计,建立Huffman树,找出最优化编码形式,因而可以增加短码字的利用率,减少长码字的使用频次.通过给出的分析和实验,说明了所提方案在附加硬件成本很低的情况下既能够提高测试数据压缩率,又能够减少测试时间,优于已发表的游程编码方案和其他同类型的编码压缩技术.     

Enhancing encoding capacity of combinational test stimulus decompressors

While scan-based compression is widely utilized in order to alleviate the test time and data volume problems,the overall compression level is dictated not only by the chain to channel ratio but also the ratio of encodable patterns.Aggressively increasing the number of scan chains in an effort to raise the compression levels may reduce the ratio of encodable patterns,degrading the overall compression level.In this paper,we present various methods to improve the ratio of encodable patterns.These methods are b...     

环形链轮询复用测试端口的高效测试结构

测试结构设计是集成电路（IC）测试的基础问题也是关键问题,而设计满足当代IC需求的测试结构对降低芯片成本、提高产品质量、增加产品竞争力具有十分重要的意义,为此提出了环形链轮询复用测试端口的测试结构RRR Scan。该结构将扫描触发器设计成多个环形链,环形链可工作于隐身模式、循环移位模式和直链扫描模式。循环移位模式实现了测试数据的重用,可减小测试集规模;隐身模式则可缩短测试数据移位路径,大幅降低测试移位功耗,因此该结构是具有数据重用和低功耗性质的通用测试结构。另外,该结构可将物理上相近的扫描单元设置于同一环形链内,布线代价不大。隐身模式使得测试数据的移位路径长度和时延均有所减小。实验结果表明,RRR Scan结构可大幅降低测试移位功耗,对于S13207电路,其移位功耗仅为扫描直链的0.42%。     

时序电路测试向量融合算法

时序电路的测试序列通常由各个单故障的测试向量组成.为了减少测试时间和功耗,提出2种测试向量融合算法.借助融合灵活性的概念,2种算法按不同的方式对向量序列进行排序,并以融合深度和代价作为评判准则,构建向量的融合过程,最终生成整个电路的测试序列.该算法与已有的Greedy算法时间复杂度相同,但性能更优.在ISCAS89部分电路上的实验结果表明,采用文中算法可使平均性能分别提高4.96%和8.23%.故障仿真结果表明,文中算法的故障覆盖率有少量提高,故障分辨率变化较小.     

基于树形解压缩器的低测试数据量方法

提出一种由异或门按照完全二叉树形状排列而成的树形向量解压缩器。该解压缩器的少数输出端需要由大部分的输入端来确定,而且该结构对其输出值的确定关系类似于扫描链中确定位的分布概率,可有效降低测试数据量。实验结果表明,对于ISCAS’89基准电路,该结构最高将测试数据量压缩了77倍。