一种用于低功耗BIST 的多重抑制LFSR 结构

本文提出了一种多重抑制的线性反馈移位寄存器（LFSR）结构来降低内建自测试（BIST）的功耗。这种结构通过矢量间的距离而不是矢量本身来抑制对测试没有贡献的测试矢量子序列。用来估算功耗的电路内部WSA（Weighted Switching Activity）平均降低了80.3%。此外，这种结构的另一个优点是：随着抑制次数的增加，面积开销的增加量要比其他的过滤和抑制技术要小的多。     

单/双跳变向量插入式低功耗BIST设计方法

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BIST(built-in self-test)设计方法,该方法在原始线性反馈移位寄存器LFSR(linear feedback shift register)的基础上加入若干逻辑,使测试向量每周期最多产生两次跳变,因而大大降低了被测电路CUT(circuit under test)的功耗。通过对组合电路集ISCAS’85的实验证明,被测电路的总功耗、平均功耗以及峰值功耗都有大幅度的降低。     

基于LFSR优化的BIST低功耗设计

在BIST(内建自测试)过程中,线性反馈移位寄存器作为测试矢量生成器,为保障故障覆盖率,会产生很长的测试矢量,从而消耗了大量功耗.在分析BIST结构和功耗模型的基础上,针对test-per-scan和test-per-clock两大BIST类型,介绍了几种基于LFSR(线性反馈移位寄存器)优化的低功耗BIST测试方法,设计和改进可测性设计电路,研究合理的测试策略和测试矢量生成技术,实现测试低功耗要求.     

基于LFSR优化的BIST低功耗设计

在BIST(内建自测试)过程中,线性反馈移位寄存器作为测试矢量生成器,为保障故障覆盖率,会产生很长的测试矢量,从而消耗了大量功耗。在分析BIST结构和功耗模型的基础上,针对test-per-scan和test-per-clock两大BIST类型,介绍了几种基于LFSR(线性反馈移位寄存器)优化的低功耗BIST测试方法,设计和改进可测性设计电路,研究合理的测试策略和测试矢量生成技术,实现测试低功耗要求。     

基于双模式LFSR的低功耗BIST结构

传统的BIST结构中,由于LFSR产生大量的测试矢量在测试过程中消耗了大量的功耗。为了减少测试矢量的数目而不影响故障覆盖率,我们提出了一种新的基于双模式LFSR的低功耗BIST结构。首先介绍了功耗模型和延迟模型的基础知识,然后给出了用于生成双模式LFSR的矩阵,并介绍了解矩阵方程式的算法。随后说明了新的BIST结构和用于矢量分组的模拟退火算法。最后,基于Benchmark电路的实验证明这种结构可以在不降低故障覆盖率的同时减少70％的功耗。     

面向低功耗BIST 的VLSI 可测性设计技术

随着手持设备的兴起和芯片对晶片测试越来越高的要求，内建自测试的功耗问题引起了越来越多人的关注，本文对目前内建自测试的可测性设计技术进行了分析并对低功耗的VLSI可测性设计技术的可行性和不足分别进行了探讨。在文章的最后简单介绍了笔者最近提出的一种低功耗的BIST结构。     

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。     

一种新的低功耗BIST测试生成器设计

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BIST测试生成器设计方案,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电路,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.由于该设计方案比其它LPTPG方案的面积开销小,从而具有更好的使用价值.     

面向功耗优化的伪随机测试矢量生成

随着集成电路设计复杂度和工艺复杂度的提高，集成电路的测试面临越来越多的挑战，内建自测试作为一种新的可测性设计方法，能显著提高电路中随机逻辑的可测性，解决一系列测试难题，但它同时也引起了测试功耗问题，本文提出了一种面向功耗优化的伪随机测试向量生成方法，在保证故障覆盖率的条件下，大大降低了测试功耗。     

一种减少BIST测试资源的高级寄存器分配算法

在高级综合阶段考虑电路的可测性有许多优点，包括降低硬件开销，减少性能的下降，并达到更高的测试效率等。本文提出了一种基于伪随机可测性方法的寄存器分配算法，来减少内建自测试（BIST）所带来的硬件开销。在基准电路上的实验结果表明：与其它BIST测试综合方法相比较，采用本论文所提的方法进行测试综合对测试资源占用最多可以降低46.8%.     

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 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.     

A Ring Architecture Strategy for BIST Test Pattern Generation

This paper presents a new effective Built-In Self Test (BIST) scheme that achieves 100% fault coverage with low area overhead, and without any modification of the circuit under test (CUT), i.e., no test point insertion. The set of patterns generated by a pseudo-random pattern generator, e.g. a Linear Feedback Shift Register (LFSR), is transformed into a new set of patterns that provides the desired fault coverage. To transform these patterns, a ring architecture composed by a set of masks is used. During on-chip test pattern generation, each mask is successively selected to map the original pattern sequence into a new test sequence. We describe an efficient algorithm that constructs a ring of masks from the test cubes provided by an automatic test pattern generator (ATPG) tool. Moreover, we show that rings of masks are implemented very easily at low silicon area cost, without requiring any logic synthesis tool; a combinational mapping logic corresponding to the masks is placed between the LFSR and the CUT, together with a looped shift register that acts as a mask selecting circuit. Experimental results are given at the end of the paper, demonstrating the effectiveness of the proposed approach in terms of area overhead, fault coverage and test sequence length. Note that this paper is an extended version of [1].     

一种新型混合模式BIST的低功耗设计

本文提出了一种基于折叠集的test-Der-clock结构的混合模式BIST设计方案,并且进行了低功耗的整体优化设计.该设计方案在电路结构上利用双模式LFSR将两部分测试生成器有机的进行了结合,针对伪随机测试序列与折叠测试序列两部分采用了不同的措施来优化测试生成器的设计,从而达到降低被测电路功耗的目的.     

一种低功耗双重测试数据压缩方案

随着集成电路制造工艺的发展,VLSI（Very Large Scale Integrated）电路测试面临着测试数据量大和测试功耗过高的问题.对此,本文提出一种基于多级压缩的低功耗测试数据压缩方案.该方案先利用输入精简技术对原测试集进行预处理,以减少测试集中的确定位数量,之后再进行第一级压缩,即对测试向量按多扫描划分为子向量并进行相容压缩,压缩后的测试向量可用更短的码字表示;接着再对测试数据进行低功耗填充,先进行捕获功耗填充,使其达到安全阈值以内,然后再对剩余的无关位进行移位功耗填充;最后对填充后的测试数据进行第二级压缩,即改进游程编码压缩.对ISCAS89基准电路的实验结果表明,本文方案能取得比golomb码、FDR码、EFDR码、9C码、BM码等更高的压缩率,同时还能协同优化测试时的捕获功耗和移位功耗.     

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.