一种新的故障测试率的概率估计方法

A NEW PROBABILISTIC APPROACH TO ESTIMATE TESTABILITY

本文提出了一种新的估计故障测试率的方法。它使用了无故障模拟的概念,观察率和控制率被定义成观察和控制电路节点的概率;分析了电路中节点的随机信号的概率分布;证明了控制率是服从正态分布的;依此获得了故障测试率的无偏估计。按照观察率的定义,我们处理了扇出节点。对一些实际的电路,利用此法所获得的故障覆盖与故障模拟结果非常吻合。

A new approach to calculate fault detection probabilities is presented. The fault-free simulation is used in this approach. The quantities of controllabilities and observabilities are defined as probabilities of controlling and observing the nodes in the circuit. The probability distribution of random signals at circuit nodes is analyzed, and it is proved that controllability is in normal distribution. Thus the unbiasing estimate of fault detection probability can be obtained. According to the concept of observability, the fanout nodes are dealt with. For actual circuits the fault coverage obtained from this approach agrees favorably with the fault simulation results.