Investigation and Mitigation of Radio Frequency Interference Caused by Weak Grounding of USB Type-C Receptacle Connector

In modern mobile electronic systems, USB connector has been identified as one of the dominant noise sources for desense issues. In this paper, the noise coupled to the Wi-Fi antenna from a USB connector is investigated. With the assistance of full-wave simulations, the root cause of desense noise is identified as the non-ideal electrical connection between the metal chassis and the USB receptacle shell where it is installed. The proposed radiation mechanism is validated through measurements of a real tablet device, and 15 dB noise level reduction is observed with a better grounding structure.

I. Introduction

With the increasing complexity and miniaturization of modern mobile platforms, including mobile phones, tablets, and laptops, the distances between antennas and high-speed integrated circuits (ICs) or connectors are driven closer, which intensify the radio frequency interference (RFI) issue. In addition, the ever-growing demands for higher data transfer rate make the matter worse. As discussed in [1], the noise could be generated by different noise sources, such as liquid-crystal displays [2], digital microphones [3] and switching power supplies [4].