提出一种测试码压缩方法,首先切分测试集中含确定位较多的难以编码的测试向量,然后与未被切分的测试向量共同组成新的测试集,并将新测试集编码成线性反馈移位寄存器(LFSR)种子,从而实现测试数据压缩.该方法提高了LFSR的编码效率,取得了稍优于混合码的压缩率.与混合码复杂的解压结构相比,在硬件开销上具有明显的优势,仅需一个LFSR和简单的控制电路,且通信协议简单。
In a test set, some patterns have a lot of specified bits and are hardly encoded by LFSR. They are syncopated and substituted by generating patterns. This paper presents a scheme for test pattern compression. In the scheme, a new test set is produced and then is encoded as LFSR seeds. The proposed method increases probability of successful encoding and achieves better compression ratio than the hybrid coding. It also has a simple decoding circuit which outperforms the hybrid coding. The decoding hardware consists of an LFSR and a small control circuit. Furthermore, the communication protocol is simple.