A free-shape router for analog and RF applications

In this paper, a new method for routing is presented that computes routes as piecewise connected polygons. First, it creates routes based on a modified Lee approach that prefers 45-degree connections. Second, the resulting routes are developed to shortest piecewise linear segments of any angle between pins and around corners of blocked areas. The underlying algorithm for this second step can be interpreted as constrained stretching on Lee routes. In a third step of the method, the piecewise linear segments are inflated to polygons considering constraints, e.g., from blocked areas. The result is a routing of nearly free shape, which is especially suited for RF applications. Experimental results show the effectiveness and efficiency of the presented method.