隨著製程的快速演進，錯誤診斷將變得越來越重要，在此論文中，我們提出了兩個技術來提升錯誤診斷的品質，第一個技術利用高效能的診斷向量產生器產生測試向量來分開錯誤對或是辨別等效錯誤對，第二個技術則是利用加入觀測點的方式來區分錯誤對。我們主要用兩個方法來產生診斷向量，第一個方法為錯誤失活法，在產生診斷向量時只激活其中一個錯誤，另一個錯誤保持未激活的狀態，藉此分開錯誤對;第二個方法為錯誤傳遞法，在產生診斷向量時同時激活兩個錯誤，並使得這兩個錯誤在觀測端可以觀測到不同的錯誤響應。在標準電路 ISCAS89 (ITC99)的實驗結果顯示，有99.99% (99.99%)的錯誤對可以被我們的方法分開或是判斷為等效錯誤對。但仍有一些無法被處理的錯誤對，我們會利用加入一些觀測點到電路中，藉此分開這些尚未被分開的錯誤對。由實驗結果顯示，只需要加入2(109)個觀測點，在實驗電路ISCAS89 (ITC99)中所有的錯誤對皆可以被分開或是判斷成等效錯誤對，且只需增加少量的硬體面積。同時，我們也同時考慮兩個錯誤彼此間相距很遠的錯誤對，並加入插入點到電路中將這些錯誤對分開。實驗結果顯示，只需要少量的觀測點就可以將這些錯誤對分開。

Two major techniques are proposed to increase diagnosisability of circuits: 1. Diagnostic pattern generation (DPG) generates high quality diagnostic patterns to distinguish transition fault pairs and identifies equivalent fault pairs. 2. Observation point insertion inserts observation points into circuit to distinguish the fault pairs. The first technique mainly consists of two methods: 1. Fault Inactivation Method (FIM) generates diagnostic patterns to distinguish fault pairs by inactivating one fault and detecting the other. 2. Fault Propagation Method (FPM) generates diagnostic patterns to distinguish fault pairs by initializing both faults at the same time and creating different faulty responses of two faults on outputs. Experimental results show that the diagnosis resolutions in ISCAS89 (ITC99) benchmarks can reach 99.999999% (99.999995%). But few fault pairs cannot be distinguished or identified as equivalent fault pairs. We use the second technique to insert observation points to distinguish these fault pairs. Experimental results show that only 2 (109) observation points are needed for ISCAS89 (ITC99) benchmarks, and hence the diagnosis resolutions for all circuits are 100% with area overhead less than 1%. In addition, for the indistinguished fault pairs with large distance between two faults in a pair, we also adopt our second technique. Experimental results show that most of fault pairs can be distinguished by inserting few observation points.

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