An Integrated System for Assigning Signal Flow Direction to CMOS Transistors

• Main Authors: Chih Nan Wang, 王志男
• Other Authors: Kuen Jong Lee
• Format: Others
• Language: en_US
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/23839658406573614957

碩士 === 國立成功大學 === 電機工程研究所 === 81 === In many CAD tools, signal flow direction information has been used to improve their accuracy and performance. Hence deriving this information correctly and efficiently is an important and rewarding task. In this thesis an integrated system for deriving signal flow direction information is presented. This system consists of two subsystems: structure-based and rule- based. In the structure-based subsystem, a new graph-theoretic algorithm is developed. The direction assignment problem is modeled as a two-paths problem on an undirected graph called GST-graph. The GST-graph is decomposed into split components by a linear algorithm and the direction information of most edges in each split component can be derived by another linear algorithm. If all transistors in a circuit are unidirectional then all of them will be determined in this system. For those transistors that cannot be determined by this subsystem, if any, they will be dealt with in the rule-based subsystem. A new set of rules including a logic implication rule have been implemented. By considering the circuit semantics, some difficult circuit such as a barrel shifter can be solved. Experimental results show that accuracy and efficiency of this integrated system.