High-Frequency Power Supply Control for Intermodulation Suppression
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Solution Overview
Problem
High-frequency power supply devices used in plasma processing apparatuses experience intermodulation distortion due to reflected wave power fluctuations, which cannot be effectively suppressed by conventional frequency modulation control without appropriate start phase and frequency shift settings.
Innovation Solution
A high-frequency power supply device with a first and second power supply, and matching units, performs repeated search processing for the start phase and frequency shift amount of the modulation signal to minimize the reflection coefficient or reflected wave power through frequency modulation control, using a modulation signal with the same frequency as the second fundamental frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If frequency modulation control is performed with fixed start phase and frequency shift amount, then the control system is simple, but intermodulation distortion cannot be effectively suppressed
Solution Approach 1:
The patent applies dynamics by making the modulation signal parameters (start phase and frequency shift amount) variable rather than fixed. The control unit dynamically adjusts these parameters through repeated search processing to optimize intermodulation distortion suppression, transforming a static control system into an adaptive one that responds to changing conditions.
Solution Approach 2:
The patent implements feedback by using the detected reflected wave power as a feedback signal to the control unit. The control unit repeatedly searches for optimal start phase and frequency shift amount based on this feedback, creating a closed-loop control system that continuously optimizes distortion suppression while managing system complexity.
2Ease of manufacture
If the start phase and frequency shift amount are not optimized, then the frequency modulation control is simple to implement, but reflected wave power fluctuates due to intermodulation distortion
Solution Approach 1:
The system performs self-service by automatically searching for and adjusting the optimal start phase and frequency shift amount without requiring manual intervention. The control unit autonomously optimizes the frequency modulation parameters based on reflected wave power feedback, maintaining stability while keeping the implementation process automated rather than manual.
3Object-generated harmful factors
If repeated search processing is performed to optimize modulation parameters, then intermodulation distortion is suppressed, but the control processing time increases
Solution Approach 1:
The patent applies periodic action by performing repeated search processing at optimized intervals rather than continuously. The control unit periodically adjusts the start phase and frequency shift amount based on reflected wave power conditions, achieving distortion suppression while minimizing unnecessary processing and reducing time loss.
Data Source
AI summary
A high-frequency power supply device includes: a first power supply that supplies first high-frequency power to a load by outputting a first high-frequency voltage having a first fundamental frequency; a second power supply that supplies second high-frequency power to the load by outputting a second high-frequency voltage having a second fundamental frequency lower than the first fundamental frequency; a first matching unit between the first power supply and the load; and a second matching unit between the second power supply and the load. When frequency-modulating the first high-frequency voltage with a modulation signal having a same frequency as the second fundamental frequency to output a modulated wave, the first power supply repeatedly performs search processing of a start phase of the modulation signal and search processing of a frequency shift amount of the modulated wave such that magnitude of a reflection coefficient or magnitude of reflected wave power reduces.