Controlling Inductive Coupling in Wide Global Signal Busses Through Swizzling

Abstract

Recent advances in Deep Submicron (DSM) design and manufacturing technologies have brought to the forefront the importance of inductive coupling amongst long interconnect in high performance microprocessors. Inductive coupling has been shown to depend directly on the overlap length between adjacent signal wires, the activity on these wires and the distance separating them. This paper presents a technique-known as swizzling-that exploits the inductive coupling dependence on distance to reduce the effect of any particular attacker on any of its victims. In the swizzling technique, the order of signal wires in global signal busses is continuously re-arranged to move attackers and victims away from each other. This paper shows that this technique significantly reduces the inductive coupling for the most vulnerable wires neighboring the attacker with zero area and routing resource penalty.

Statistical information of crosstalk on parallel bus

“…Some physical methods imply introduction of guard traces, but then the surface needed on the PCB increases, and that means cost production and difficulties in realizing smaller devices. Other physical approaches are based on swizzling the traces, however this method has to be run again each time the statistical proprieties of the data sent are changing, [3]. Swizzling of the traces can be utilized with success on ASIC, or memory address buses, where the statistics are known.…”

“…The disadvantage of such a model is that it doesn't offer information regarding how the other traces affect the victim line. There can be great difference between an RC model and an RLC model analysis because coupling inductance it can manifest its effects at great distances, [3], and [7].…”

Reducing inductive coupling variance in wide global signal busses

“…The swizzling technique was introduced in an earlier publication (Soudan 2005). Here we examine its application for the reduction of signal transition speed variations caused by the variations in inductive coupling.…”