Text - KFUPM - King Fahd University of Petroleum and Minerals

Chapter 3
Proposed Compression Algorithms
3.1 Introduction
In this work we propose a test data compression technique that utilizes a multiple
scan chains configuration. This configuration is shown in Figure 3.1(a). The input
test set consists of n V scan test vectors, each vector configured into N scan chains of
length L each. The output of the compression algorithm is shown in Figure 3.1(b).
It contains n V ′ test vectors, where n V ′ ≥ n V , each encoded using M representative
scan chains of length L. These vectors, called representative vectors, are grouped
into n P partitions. Figure 3.2 shows the block diagram of the hardware and CUT,
where M is the number of ATE scan input channels and N denotes the number
of scan chains internal to the core feeding the scan cells. In this configuration,
N ≫ M, i.e., the compressed input test data is composed of a much smaller number
26