Isolation Transformer RF Power Circuitry
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Solution Overview
Problem
Existing RF isolation filters in plasma processing systems are bulky and complex due to high RF frequencies, requiring large air core inductors and struggling with variable RF frequencies, which complicates impedance matching and can lead to high voltage discharge, excessive heat, and power dissipation.
Innovation Solution
Employing an isolation transformer with an intermediate frequency power signal, rectified from AC and modulated to reduce size and capacitive coupling, while using a high magnetic permeability core and Faraday shields to maintain efficient RF isolation across a wide range of frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high RF frequency (MHz range) is used for plasma processing, then effective plasma generation is achieved, but large air core inductors are required making the RF filter bulky
Solution Approach 1:
The patent changes the frequency parameter by introducing an intermediate frequency (IF) stage between the low frequency power source and the high frequency RF system. The power signal is first converted to an intermediate frequency (e.g., 400 kHz to 10 MHz), then modulated onto the high frequency RF carrier. This parameter transformation allows the use of smaller inductors at the intermediate frequency while still achieving the required high frequency RF power delivery to the plasma processing system.
2Adaptability or versatility
If RF frequency tuning is employed during processing, then process flexibility is improved, but RF isolation filter design becomes significantly more challenging and complex
Solution Approach 1:
The patent introduces an intermediate frequency as a mediator between the power source and the variable frequency RF system. The intermediate frequency stage provides a stable reference that simplifies the isolation filter design, while the modulation stage handles the frequency tuning requirements. This intermediary approach allows the isolation filter to be designed for a fixed intermediate frequency, greatly reducing design complexity even when the final RF output frequency varies.
3Reliability
If conventional RF filter design is used to present high impedance to RF frequencies, then RF short to ground is prevented, but the design must handle wide range of frequencies and impedances making it complex
Solution Approach 1:
The patent segments the power delivery system into distinct frequency stages: a low frequency power source stage, an intermediate frequency conversion stage, and a high frequency RF modulation stage. Each stage has its own isolation and filtering requirements. By segmenting the system this way, the isolation filter only needs to handle the intermediate frequency with fixed impedance characteristics, rather than dealing with the full range of variable high frequencies, thus reducing design complexity while maintaining reliability.
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 approach reduces the size of the isolation transformer, minimizes capacitive coupling, and maintains high impedance to RF frequencies, providing effective RF isolation while preventing resonance and heat issues, thus simplifying the design and improving system consistency.
Implementation Method 1
an isolated power signal at an intermediate frequency is generated across a secondary winding of the isolation transformer via mutual inductance
Implementation Method 2
using a high magnetic permeability core
Implementation Method 3
Faraday shields to maintain efficient RF isolation
Data Source
AI summary
System and method for providing isolated power to a component that is also subject a set of RF signals that includes at least a first RF signal having a first RF frequency is provided. There is included providing a DC voltage signal and modulating the DC voltage signal into an isolated power signal using an isolation transformer. The isolated power signal has an intermediate frequency that is higher than 60 Hz and lower than the first RF frequency. There is included supplying the DC voltage signal to the primary winding and obtaining the isolated power signal from the secondary winding; and delivering the isolated power to the component using the isolated power signal.