A Fast Wire-Routing Method and an Automatic Layout Tool for RSFQ Digital Circuits Considering Wire-Length Matching

A fast wire-routing method considering wire-length matching of passive transmission lines (PTLs) is proposed. The method deals with channel routing between adjacent columns of active devices, and generates paths of PTLs with specified additional length packed in compact area based on simulated annealing. It uses a generation method of paths from a sequence of symbols for searching solutions efficiently. An automatic layout tool is also shown. It consists of a placer and a router based on the proposed method. The placer uses total extension length of PTLs for length matching as one of the evaluation metrics for detailed placement using simulated annealing. By introducing this metric, total extension length in routing phase is reduced and compact layouts are obtained. Using the tool, design flow from HDL descriptions to layout generation can be established. As an experimental result, a layout of an adder designed by the tool is shown.