Improved gate matrix layout

A two-stage approach to gate matrix layout is described. The approach consists of: the determination of an optimal gate sequence and an assignment of nets to rows such that the nets are realizable. The gate sequence algorithm is based on T. Asano's approximate search (1981). Modifications are made to it to take into account constraints of transistor sizing, serial subcircuit conflicts, input/output (I/O) gates, and I/O nets. The zone-net assignment algorithm assigns nets to a minimum number of rows determined by the gate sequence and provides a means to resolve vertical conflicts in the layout. Power connections are implemented using the power nets and possible added power rows. Results of examples show that the approach can achieve a considerable improvement compared to earlier algorithms, while satisfying additional constraints.<
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