FXT-Route: Efficient High-Performance PCB Routing with Crosstalk Reduction Using Spiral Delay Lines

Abstract

In high-performance printed circuit boards (PCBs), adding serpentine delay lines is the most prevalent delay-matching technique to balance the delays of time-critical signals. Serpentine topology, however, can induce simultaneous accumulation of the crosstalk noise, resulting in erroneous logic gate triggering and speed-up effects. The state-of-the-art approach for crosstalk alleviation achieves waveform integrity by enlarging wire separation, resulting in an increased routing area. We introduce a method that adopts spiral delay lines for delay matching to mitigate the speed-up effect by spreading the crosstalk noise uniformly in time. Our method avoids possible routing congestion while achieving a high density of transmission lines. We implement our method by constructing a mixed-integer-linear programming (MILP) model for routing and a quadratic programming (QP) model for spiral synthesis. Experimental results demonstrate that our method requires, on average, 31% less routing area than the original design. In particular, compared to the state-of-the-art approach, our method can reduce the magnitude of the crosstalk noise by at least 69%.