Integrated Common-Mode EMI Filter with ESD Protection
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Solution Overview
Problem
Existing common-mode choke coils are too large and thick for modern electronic devices, particularly smartphones, and fail to provide adequate noise attenuation across the 700-2500 MHz spectrum, making them unsuitable for high-speed electronics that require integrated EMI filtering with electrostatic discharge (ESD) protection.
Innovation Solution
A common-mode EMI filter integrated circuit (IC) with integrated ESD protection is developed, featuring coupled spiral inductor coils on a high-resistance substrate with a dielectric layer, utilizing advanced IC processes and metal redistribution layer (RDL) techniques to create a compact, high-efficiency filter with minimal series resistance and optimal magnetic coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If discrete common-mode choke coils are used, then high common-mode rejection can be achieved, but the footprint becomes large and thick
Solution Approach 1:
The patent combines the common-mode filter function with ESD protection components into a single integrated circuit device. The CMF circuit includes primary and secondary coils formed on a substrate with high-resistance layers, integrating multiple functions that were previously implemented with separate discrete components, thereby reducing overall footprint while maintaining common-mode rejection performance
Solution Approach 2:
The patent transitions from three-dimensional wire-wound or laminate choke coils to a planar two-dimensional implementation using printed circuit board traces and high-resistance substrate layers. This dimensional change enables compact integration while achieving the required magnetic coupling through careful layout design of the primary and secondary coils
2Loss of energy
If wire-wound or laminate common-mode choke coils are used, then low series resistance can be achieved, but the device becomes too thick for modern electronics
Solution Approach 1:
The patent integrates the CMF circuit with ESD protection components and high-resistance substrate layers into a single thin-profile device. The primary and secondary coils are formed using conductive traces on the substrate with high-resistance layers providing both structural support and electrical isolation, eliminating the need for thick wire-wound or laminate constructions
Solution Approach 2:
The patent uses substrate materials with high electrical resistance (greater than 1000 Ω·cm) to provide both mechanical support and electrical isolation functions. This parameter change in substrate resistivity enables the coils to be formed as planar traces rather than requiring thick insulating layers, reducing overall device thickness while maintaining low series resistance through optimized trace geometry
3Ease of manufacture
If discrete common-mode choke coils are used, then simple fabrication can be achieved, but integration with ESD protection is not possible
Solution Approach 1:
The patent combines the common-mode filter circuit with ESD protection components into a single integrated device fabricated using standard PCB processes. The primary and secondary coils, high-resistance substrate layers, and ESD protection elements are all formed in the same manufacturing sequence, enabling integration while maintaining fabrication simplicity through conventional printing, etching, and lamination techniques
Solution Approach 2:
The patent creates a multi-functional device that provides both common-mode filtering and ESD protection in a single component. The high-resistance substrate serves multiple functions including structural support, electrical isolation, and noise suppression, while the integrated circuit design allows the same device to protect against both electromagnetic interference and electrostatic discharge events
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
The solution provides a thin and small footprint common-mode EMI filter with high common-mode rejection and low differential-mode loss, effectively suppressing noise while maintaining signal integrity, and can be integrated into single-chip or multiple-chip modules for advanced electronic systems.
Implementation Method 1
a primary spiral inductor coil, a secondary spiral inductor coil, a dielectric layer between the two coils... The primary spiral inductor coil and the secondary spiral inductor coil are disposed corresponding to each other
Implementation Method 2
The resistivity of the high-resistance substrate is more than 100 Ω-cm
Implementation Method 3
a dielectric layer between the two coils... The dielectric layer separates the primary spiral inductor coil from the secondary spiral inductor coil electrically
Data Source
AI summary
An integrated circuit common-mode electromagnetic interference filter incorporating electro-static discharge protection comprising two inductive coils is provided. A pair of primary and secondary spiral inductor coils is disposed corresponding to each other. A dielectric layer is used to separate the primary spiral inductor coil from the secondary spiral inductor coil electrically. Resistivity of a high-resistance substrate is more than 100 Ω-cm for supporting the primary spiral inductor coil, the secondary spiral inductor coil and the dielectric layer thereon. The proposed filter structure can be formed in integrated circuit (IC) back-end processes and thus be extraordinarily advantageous of effectively eliminating electromagnetic interferences and having electrostatic protection effect at the same time, while having small footprint.