An efficient paired-net routing algorithm for high-speed bipolar LSIs

This paper proposes an efficient paired-net routing algorithm. A paired net consists of two nets assigned to adjacent tracks and columns. The paired-net routing approach is applied for differential drive nets in a bipolar ECL LSI to decrease signal skew and enhance signal integrity. Paired nets can cause a new type of cyclic constraint, which does not appear in the conventional vertical constraint graph. To wire these paired nets, the new type of cyclic constraint must be detected and resolved. We applied our approach to two actual bipolar ECL circuits: a 4.0-k-gate circuit, which operated at 3 Gbit/s, and a 5.6-k-gate circuit, which operated at 2.5 Gbit/s. The experimental results verify the effectiveness of our paired-net routing approach