RF Power Amplifier Assembly With Shielded Cooling Plate Isolation
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Solution Overview
Problem
RF power amplifiers in MRI systems suffer from poor electromagnetic interference compatibility (EMC) performance, leading to RF and spurious emissions that degrade image quality and pose safety risks.
Innovation Solution
A radio frequency amplifier assembly with an electrically conductive housing and cooling plate that divides the interior into isolated regions, incorporating a grounding path and shielding enclosure to enhance EMC performance, and a method of assembling the amplifier with a shielding cabinet and shortened cable routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If RF power amplifier is used to generate high power RF pulses for MRI, then the power output is improved, but RF and spurious emissions increase causing poor EMC performance
Solution Approach 1:
The amplifier is divided into multiple isolated sections using partition walls within the housing. Each section containing specific components (oscillator, amplifier stages, power supply) is electrically isolated from others, preventing RF emissions from propagating between sections and improving overall EMC performance while maintaining high power output capability
Solution Approach 2:
Different sections of the amplifier housing are assigned different shielding and grounding characteristics based on their specific RF emission risks. High-power amplifier sections receive enhanced shielding, while low-power control sections use standard shielding, optimizing EMC performance without unnecessary complexity throughout the entire device
2Device complexity
If multiple electronic components are arranged within the heat sink for compact design, then the device complexity is reduced, but electromagnetic interference between components increases
Solution Approach 1:
The heat sink is divided into multiple thermally coupled but electrically isolated sections using non-conductive thermal interface materials and insulating barriers. This allows multiple electronic components to be mounted on different heat sink sections for compact thermal management while preventing electromagnetic interference between adjacent components through electrical isolation
Solution Approach 2:
Non-conductive thermal interface materials and insulating barriers are introduced between electronic components mounted on the heat sink. These intermediary materials provide thermal coupling for heat dissipation while simultaneously providing electrical isolation to prevent electromagnetic interference, resolving the conflict between compact design and EMI reduction
3Ease of manufacture
If feed-through connectors are used to connect isolated PC boards, then the ease of manufacture is improved, but RF propagation along the feed-through increases causing interference
Solution Approach 1:
RF filtering circuits and ferrite beads are introduced as intermediary elements on the feed-through connectors and signal paths. These intermediaries allow the feed-through connectors to maintain their manufacturing simplicity while the added filtering elements block RF propagation and spurious emissions along the connector paths, eliminating interference without complicating the basic connector architecture
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 effectively prevents RF interference, improving EMC performance without adding new components or costs, thereby enhancing image quality and safety in MRI systems.
Implementation Method 1
an electrically conductive cooling plate disposed inside the electrically conductive housing and having a first side and an opposite second side, the electrically conductive cooling plate being configured to divide the enclosed interior into a first enclosed region and a second enclosed region
Implementation Method 2
an electrically conductive housing that defines an enclosed interior of the radio frequency amplifier assembly
Implementation Method 3
electrically conductive cooling plate disposed inside the electrically conductive housing
Data Source
AI summary
Radio frequency amplifier (200) assembly with effective prevention of RF interference. The radio frequency amplifier comprises an electrically conductive housing (301) that defines an enclosed interior of the radio frequency amplifier assembly, an electrically conductive cooling plate (415) disposed inside the electrically conductive housing and having a first side and an opposite second side, the electrically conductive cooling plate being configured to divide the enclosed interior into a first enclosed region (501) and a second enclosed region (503), and a radio frequency signal processing circuit board (223) equipped with a radio frequency signal processing circuit, the radio frequency signal processing circuit board being positioned in the first enclosed region and disposed on the first side of the electrically conductive cooling plate, and a power supply module and a controller module positioned in the second enclosed region and disposed on the opposite second side of the electrically conductive cooling plate.