Prediction and verification of power/ground plane edge radiation excited by vias based on balanced TLM and Via coupling model

Abstract

In modern high-performance digital devices, packages, and systems, clock frequency and its harmonics are elevated to GHz frequency ranges. Furthermore, power supply and ground return current exceeds tens of amperes to drive numbers of I/O drivers and digital core circuits. The device, package, and system density is also high. The combined effect of the high-frequency current spectrum components and the high power supply and I/O current raise serious design concerns and challenges in controlling the resulting radiated field emission. One of the radiated field emission problems is from the power/ground plane cavity edge. However, it is too difficult to analyze due to the complex structure like multi-layer stack-up, and it is needed to efficiently simulate to predict the radiated field emission from the power/ground plane cavity edge. In this dissertation, a balanced TLM and via coupling model is proposed for efficient simulation of radiated field emission from a power/ground plane cavity edge, where the radiated field emission is excited by vias in a multilayer package and PCB (printed circuit board). The proposed model can efficiently express skin depth effect and return current discontinuity of via, which are the reason for making the analysis difficult and complex. Also, it uses unit cell concept to easily express spatial effect of the via. The radiated field emission is simulated and measured with a series of test boards. The simulation agrees fairly well with the measurement confirming the preciseness and usefulness of the proposed model. It is shown that the via is a considerable source of the radiated field emission as well as the signal loss. The effect of a decoupling capacitor fence (De-Cap Fence) at the edge of the board to mitigate the radiated field emission is examined. The proposed model confirms that the De-Cap Fence changes the resonance mode and frequency of the plane cavity, and reduces the radiated field emission. And the effect of clock on th...