一种基于TRC-LFSR结构的二维测试向量压缩设计

Design of the 2-dimensional test patten compression based on TRC-LFSR structure

基于扭环计数器TRC和线性反馈移位寄存器LFSR,提出了一种可实现二维测试向量压缩的测试向量生成器.采用基于TRC的测试集嵌入技术实现测试向量集的垂直压缩,利用LFSR重播种技术实现测试向量集的水平压缩,从而显著地减少确定性测试向量集的长度和宽度.理论分析表明,采用该设计编码一个含有smax个确定位的测试向量所需的LFSR长度从smax+20减小到smax+2,提高了编码效率.为了减少所需LFSR种子的个数,提出了一种有效的LFSR种子选择算法.这里,每个LFSR种子首先被解码成TRC种子,再由TRC种子产生2n2+n的测试向量.针对ISCAS89实验电路的实验结果表明,相对于现有的算法,采用该设计实现的测试电路,存储位数最大可减少69%,并且测试控制逻辑电路简单,可重用性好.

Based on the twisting-ring counter （TRC） and linear feedback shift register （LFSR）, a kind of test pattern generator, which can realizes two-dimensional test pattern compression is presented. The proposed approach utilizes the test set embedding technique based on TRC and LFSR reseeding schemes to achieve the vertical and horizontal compressions of the test set, which significantly reduces the width and length of the deterministic test set. Theoretical analysis shows that the length of LFSR of the design is reduced up to Smax ＋2 from smax ＋20, which increases the encoding efficiency. In order to target the minimization of the number of the LFSR seeds, an efficient LFSR seed selection algorithm is then proposed. Here, each LFSR seed is decoded as a TRC seed, and then, the TRC seed generates 2n^2 ＋n test patterns. Experimental results for the ISCAS89 benchmark circuits show that the proposed scheme requires 69% less test data storage compared with previous schemes, and that the test control logic is simple for all CUTs, and can be shared among multiple CUTs.