A routing system for mixed A/D standard cell LSI's

Global and detailed routing algorithms that minimize crosstalk noise between signal lines are described. In mixed analog/digital circuits, crosstalk noise causes chip performance degradation. Thus, the proposed global routing algorithm routes analog nets in the independent area of the digital nets as much as possible. Both the global and detailed routers minimize the number of signal-line crossovers, especially for analog nets, as these crossovers are dominant in crosstalk noise. Double width lines can be used to avoid unexpected voltage drops caused by parasitic resistances. A postprocess automatically puts up shield lines for very noise sensitive wirings to improve the S/N ratio. The experimental results show that the proposed algorithms are effective in reducing the number of crossovers and redundant vias.<<ETX>>