PCB Resonance Plate Layout for Common-Mode EMI Suppression
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Solution Overview
Problem
Conventional resonators require a large area to achieve desired resonant frequencies, failing to meet the demand for high-density arrangements in optical transceivers, which leads to ineffective suppression of unwanted electromagnetic waves generated by differential amplifier circuits.
Innovation Solution
A printed circuit board design incorporating an electromagnetic resonance plate connected to a ground conductor and vias, forming an electromagnetic field confinement structure that resonates with and impedes the propagation of unwanted electromagnetic waves, while maintaining a compact layout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional resonator is used to suppress unwanted electromagnetic waves, then the electromagnetic wave suppression is achieved, but the area occupied is large
Solution Approach 1:
The invention transitions from a planar resonator design to a three-dimensional electromagnetic field confinement structure using vias that extend through dielectric layers. This vertical dimensionality change allows the resonator to achieve desired electromagnetic suppression with reduced footprint area, directly resolving the contradiction between suppression effectiveness and area occupation.
Solution Approach 2:
The resonator structure is nested within the existing PCB layer structure, with the electromagnetic field confinement structure integrated into the dielectric layers between signal traces. This nesting approach allows the resonator to occupy space within the existing board thickness rather than requiring additional lateral area, solving the area constraint problem.
2Area of stationary object
If the resonator area is reduced to achieve high density arrangement, then the area is reduced, but the electromagnetic wave suppression becomes insufficient
Solution Approach 1:
The invention changes the geometric parameters of the resonator by introducing via holes that extend vertically through dielectric layers, creating a three-dimensional confinement structure. This parameter change allows the resonator to maintain effective electromagnetic suppression with a smaller planar footprint, resolving the contradiction between area reduction and suppression effectiveness.
Solution Approach 2:
The resonator employs a composite structure combining conductive materials (for the resonator traces and via coatings) with dielectric materials (the PCB substrate and insulating layers). This composite approach enables the resonator to achieve enhanced electromagnetic field confinement and suppression performance within a compact area, directly addressing the contradiction.
3Object-affected harmful factors
If a large area resonator is used, then the electromagnetic wave suppression is effective, but the manufacturing cost increases
Solution Approach 1:
By utilizing the vertical dimension through via holes that extend through dielectric layers, the resonator achieves effective electromagnetic suppression without requiring a large planar area. This reduces the amount of copper material needed and allows for more compact PCB designs, thereby reducing manufacturing costs while maintaining suppression effectiveness.
Solution Approach 2:
The via holes serve multiple functions: they provide mechanical support, electrical grounding, and electromagnetic field confinement. This multi-functionality reduces the need for separate structures, simplifying the manufacturing process and reducing overall production costs while maintaining effective electromagnetic wave suppression.
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 design effectively suppresses unwanted electromagnetic waves by resonating with the common-mode signal component, allowing for high-density arrangements without degrading differential signal propagation and reducing manufacturing costs.
Implementation Method 1
the electromagnetic resonance plate being capable of resonating with an unwanted electromagnetic wave propagating through the differential transmission line pair
Implementation Method 2
The conductor plate and the vias constitute an electromagnetic field confinement structure. The electromagnetic resonance plate is capable of resonating with an unwanted electromagnetic wave propagating through the differential transmission line pair
Data Source
AI summary
A printed circuit board includes: a conductor plate below the inner dielectric layer; some vias through the inner dielectric layer, bonded to the conductor plate, centered at respective points on an upper surface of the conductor plate; a ground conductor above the inner dielectric layer, bonded to the vias, extending outwardly from any quadrangle with vertices being the nearest four points of the points; an electromagnetic resonance plate above the inner dielectric layer and inside the quadrangle, electrically connected to the ground conductor and the vias with a portion other than a protruding outer edge serving as a junction; an upper dielectric layer above the electromagnetic resonance plate; and a differential transmission line pair composed of a pair of strip conductors overlapping with the electromagnetic resonance plate, above the upper dielectric layer. The conductor plate and the vias constitute an electromagnetic field confinement structure.