Connector Shield Case Impedance Matching USB 3.0
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Solution Overview
Problem
Conventional connectors experience impedance mismatches between USB 3.0 and USB 2.0 signal terminals, leading to signal skew and degradation of high-frequency characteristics due to the absence of terminals next to certain signal terminals, which complicates the configuration by requiring additional dummy GND terminals.
Innovation Solution
The connector employs a conductive shield case with adjustable adjacent portions to function as pseudo-GND terminals, adjusting the width of these portions to match impedances between USB 3.0 and USB 2.0 terminals without adding dummy GND terminals, thereby maintaining a simple configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dummy GND terminals are added next to the TX- signal terminal and RX+ signal terminal, then the impedance of these terminals can be reduced, but the number of components and device complexity increases
Solution Approach 1:
The shield case is designed to serve dual functions: providing electromagnetic shielding and acting as a reference potential (pseudo-GND) for impedance matching. By extending the adjacent portion of the shield case to be adjacent to the second terminal, the structure uses itself to provide the reference potential that would otherwise require separate dummy GND terminals, thereby reducing component count while achieving impedance control
Solution Approach 2:
The shield case is transformed from a single-function component (electromagnetic shielding only) to a multi-functional component that simultaneously provides shielding and impedance reference. The adjacent portion of the shield case performs both its traditional shielding role and serves as a pseudo-GND terminal for impedance matching, eliminating the need for dedicated dummy GND terminals
2Manufacturing precision
If the distance between the second terminal and the adjacent portion of the shield case is reduced, then the impedance of the second terminal decreases, but the width of the terminal or shield case must be extended
Solution Approach 1:
The shield case is designed with non-uniform geometry, where the adjacent portion is extended locally to be adjacent to the second terminal while other portions maintain their original dimensions. This localized extension allows impedance control for specific terminals without requiring uniform expansion of the entire shield case or terminal structure
Solution Approach 2:
The impedance of the second terminal is controlled by adjusting the distance parameter between the terminal and the adjacent portion of the shield case. By changing this geometric parameter (distance), the impedance can be precisely matched to the first terminal without altering the fundamental structure or adding components
Data Source
AI summary
The invention provides a connector including a body having insulating properties, a conductive shield case surrounding the body, and a first terminal group arrayed in a line in the body. The first terminal group includes a first terminal and a second terminal. The second terminal is disposed adjacent to the first terminal and having a higher impedance than the first terminal. The shield case includes an adjacent portion that is adjacent to at least a portion of the second terminal and on an opposite side to the first terminal. At least one of the portion of the second terminal and the adjacent portion of the shield case is extended in width so as to shorten a distance between the portion of the second terminal and the adjacent portion of the shield case in accordance with an impedance difference between the first terminal and the second terminal.