SOI RF Module Ground Web for Active-Device RFI Mitigation
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Solution Overview
Problem
As RF devices shrink in size, managing RF noise emissions and radio frequency interference (RFI) between active devices becomes increasingly challenging, particularly in high-power applications like 5G New Radio, which hinders the miniaturization of RF packaged modules without altering signal characteristics.
Innovation Solution
A silicon-on-insulator (SOI) radio frequency module with a polysilicon ground web is introduced to conduct RF noise to a circuit ground, reducing RFI by forming a network of ground paths across the insulating substrate, thereby mitigating interference between active devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the footprint of SOI RF devices is shrunk to achieve miniaturization, then device size is reduced, but RF noise and RFI from neighboring active devices increase
Solution Approach 1:
The ground connection is segmented into multiple ground paths distributed across the insulating substrate, rather than using a single ground connection. This segmentation allows RF noise from each active device to be conducted to ground through its own dedicated path, reducing interference between neighboring devices while maintaining compact footprint
Solution Approach 2:
The insulating substrate is utilized as an intermediary medium by forming a polysilicon ground web within it. This ground web acts as a mediator that conducts RF noise from active devices to circuit ground through the insulating substrate, transforming the substrate from merely a structural element to an active noise mitigation component
2Productivity
If high-power active devices are operated in compact area to increase device density, then productivity is improved, but RFI between neighboring active devices increases
Solution Approach 1:
Different regions of the insulating substrate are given different functions: some regions contain ground paths for noise conduction, while other regions maintain electrical isolation between devices. This local differentiation allows high device density while managing RFI through spatially distributed ground connections
Solution Approach 2:
The ground web is formed within the insulating substrate layer, utilizing the vertical dimension and internal structure of the substrate rather than adding external shielding structures. This approach maintains compact device density while providing effective RFI mitigation through the substrate's internal ground paths
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 polysilicon ground web effectively attenuates RF noise without altering signal characteristics, allowing for increased density of circuit elements and reducing RFI within and between RF modules.
Implementation Method 1
The ground paths effectively conduct RF noise to a circuit ground, causing the polysilicon ground web to eliminate or substantially attenuate RFI caused by the active devices
Data Source
AI summary
Disclosed is a silicon on insulator (SOI) radio frequency (RF) module with noise reduction shielding to mitigate radio frequency interference (RFI) between active circuit devices within the module. The RF module includes various semiconductor active devices disposed upon an insulating substrate. The RF module can be a front-end module (FEM) with one or more charge pumps as active devices. A polysilicon web extends between and underneath the devices to create a network of ground paths across a surface of the insulating substrate. The ground paths effectively conduct RF noise to a circuit ground, causing the polysilicon ground web to eliminate or substantially attenuate RFI produced by the active devices without altering signal characteristics of the RF module. The disclosed solution also reduces RF noise leakage into the substrate, and can reduce RFI between neighboring RF modules.