Optical Module Shielding Cage for EMC Compliance
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Solution Overview
Problem
High-speed optical modules experience significant electromagnetic radiation issues due to high-speed signal lines, leading to compromised Electro Magnetic Compatibility (EMC) performance, which interferes with the operation of other devices.
Innovation Solution
The implementation of a shielding cage formed by two ground planes and multiple metal vias on a circuit board, encasing high-speed signal lines to effectively reduce electromagnetic radiation leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-speed signal lines are used in optical modules, then transmission speed and data rate are improved, but electromagnetic radiation increases and EMC performance deteriorates
Solution Approach 1:
A shielding cage structure is introduced as an intermediary element between the high-speed signal lines and the external environment. The shielding cage includes a first ground plane, a second ground plane, and multiple metal vias connecting them, forming a Faraday cage that mediates the electromagnetic field and prevents radiation leakage while allowing the high-speed signal lines to function at full speed.
Solution Approach 2:
The shielding cage creates an electromagnetic inert environment by enclosing the high-speed signal lines within a grounded metallic structure. This inert electromagnetic environment prevents the signal lines from radiating energy outward while maintaining their high-speed transmission capability, effectively isolating them from external electromagnetic interference and preventing them from becoming sources of interference.
2Reliability
If shielding structures are added to reduce electromagnetic radiation, then EMC performance is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The shielding cage is merged with the circuit board structure itself rather than being a separate component. The first and second ground planes are integrated into the circuit board layers, and the metal vias are formed during the standard PCB manufacturing process. This merging approach provides effective EMC shielding while minimizing additional complexity and maintaining compatibility with conventional manufacturing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly improves the EMC performance of optical modules by containing electromagnetic radiation, ensuring stable operation and compliance with EMC requirements.
Implementation Method 1
At least a part of the high-speed signal line is enclosed in a shielding cage which is formed by the first ground plane, the second ground plane and a plurality of metal vias connecting the first ground plane and the second ground plane in a way that the at least a part of the high-speed signal line is electromagnetic shielded by the shielding cage
Data Source
AI summary
The present disclosure provides an optical module, including a circuit board, an optical chip and an optical chip driver. Where the circuit board includes a first layer provided with a first ground plane, a second layer provided with a second ground plane and a high-speed signal line between the first ground plane and the second ground plane. At least a part of the high-speed signal line is enclosed in a shielding cage which is formed by the first ground plane, the second ground plane and a plurality of metal vias connecting the first ground plane and the second ground plane in a way that the at least a part of the high-speed signal line is electromagnetic shielded by the shielding cage.