Investigating a guard trace ring to suppress the crosstalk due to a clock trace on a power electronics DSP control board

The grounded guard trace ring is usually utilized to suppress the crosstalk noise interference in high-speed printed circuit boards or IC packages. Although the guard ring can reduce crosstalk, its performance is greatly affected by the effectiveness of its design. This paper first investigates the mechanism of the crosstalk noise cancellation with a grounded guard ring. The paper then discusses and analyzes several grounding patterns. Based on this investigation, guidelines to improve the performance of a guard ring are proposed. It is found that the best grounding patterns for guard trace ring is to ground at the two ends instead of using multi-point grounding. The theoretical analysis and the developed technique are verified by electromagnetic (EM) field distribution plots and the 4-ports scattering parameters that are simulated in ANSYS HFSS 3D electromagnetic simulation software. Experiments were finally conducted to validate the analysis and the proposed technique.