Early probabilistic noise estimation for capacitively coupled interconnects

Abstract

One of the critical challenges in today's high performance IC design is to take noise into account as early as possible in the design cycle. Current noise analysis tools [1, 7} are effective at analyzing and identifying noise in the post-route design stage when detailed parasitic information is available. However, noise problems identified at this stage of design cycle are very difficult to fix due to the limited flexibility in the design and may cause additional iterations of routing and placement, adding costly delays to time-to-market. In this paper, we introduce an estimated, congestion-based pre-route noise analysis approach to identify post-route noise failures before the actual detailed route is completed. We introduce new methods to estimate the RC characteristics of victim and aggressor lines, their coupling capacitances and the aggressor transition times before routing is performed. The approach is based on congestion information obtained from a global router. Since the exact location and relative position of wires in the design is not yet available at this point, we propose a novel probabilistic method for capacitance extraction. We present results on two high performance microprocessors in 0.18m technology that demonstate the effectiveness of the proposed approac.