Active Shielding Approaches to Global Signaling



Primary Contact

Himanshu Kaul

We propose the concept of active shields – shields that switch concurrently with a signal wire of interest. Active shields aid signal transitions through the coupling between the signal wire and shields. For RC dominated wires, the active shields switch in the same phase as the signal wire since capacitive coupling is the dominant coupling mechanism. For wires with dominant inductive coupling, active shields switch in the opposite phase of the signal wire. We show that under fixed area and input capacitance constraints, in-phase active shielding outperforms traditional (passive) shielding and wire sizing/spacing techniques for minimizing delays and transition times on RC-dominated wires. For RLC wires, we demonstrate a region of feasibility (in terms of signal wire widths) for which opposite-phase active shielding outperforms the passive shielding technique. Opposite-phase active shielding suppresses ringing behavior to a greater degree than passive shields, providing similar performance to differential signaling while maintaining the simplicity of single ended signaling. The benefits of opposite-phase active shielding as compared to passive shielding are shown in the context of various clock net optimizations where reductions in ringing behavior (up to 4.5X) and transition times (up to 40% reduction) are achieved.


Clock Net Optimization Using Active Shielding

Himanshu Kaul, Dennis Sylvester, David Blaauw, “Clock Net Optimization Using Active Shielding,” IEEE European Solid-State Circuits Conference (ESSCIRC), September 2003, pg. 265-268. ©IEEE



Active Shielding of RLC Global Interconnects

Himanshu Kaul, Dennis Sylvester, David Blaauw, “Active Shielding of RLC Global Interconnects,” ACM/IEEE Workshop on Timing in Synthesis and Specification (TAU), December 2002, pg. 98-104 ©IEEE