RF Impedance Matching Using Virtual Admittance for Multistate Pulses
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Solution Overview
Problem
Conventional impedance matching techniques in RF power delivery systems for plasma fabrication are inefficient in achieving precise impedance matching, especially with multistate pulses, leading to longer times and fewer iterations to reach an optimal impedance match, and are limited by the speed and accuracy of motor-controlled variable capacitors.
Innovation Solution
A controller system that generates a virtual admittance based on sensed parameters from a pulsed RF signal, adjusting capacitance and frequency to optimize impedance matching, using a mixing module to combine admittances and an impedance matching module to command adjustments in the impedance matching network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional impedance matching techniques are used with multistate pulses, then impedance matching can be achieved, but the process requires longer time and more iterations
Solution Approach 1:
The system performs preliminary sensing of RF signal parameters (voltage, current, forward power, reverse power) at multiple states within each pulse cycle, and pre-calculates the virtual admittance before executing impedance matching adjustments. This preliminary action allows the system to anticipate required adjustments rather than reacting iteratively, significantly reducing the time to achieve impedance matching while maintaining high accuracy.
Solution Approach 2:
The invention replaces traditional motor-controlled mechanical variable capacitors with electronically controlled capacitance adjustment. The controller directly adjusts capacitance values based on calculated virtual admittance, eliminating the mechanical inertia and slow response of motor-driven systems. This substitution enables rapid, precise impedance matching without the time constraints of mechanical adjustment systems.
2Measurement precision
If motor-controlled variable capacitors are used for impedance matching, then capacitance adjustment is possible, but the speed and accuracy are limited
Solution Approach 1:
The system replaces motor-controlled mechanical variable capacitors with electronically controlled capacitance adjustment mechanisms. The controller directly modifies capacitance values through electronic signals based on the calculated virtual admittance, eliminating mechanical inertia and slow response characteristics. This enables rapid, precise capacitance adjustment without the speed and accuracy limitations of motor-driven systems.
Solution Approach 2:
The invention changes the control parameter from mechanical position (motor angle) to electrical parameter (capacitance value). By directly controlling capacitance through electronic means rather than mechanical rotation, the system achieves both high speed response and high precision adjustment. The virtual admittance calculation provides the optimal capacitance parameter directly, enabling accurate and rapid impedance matching.
3Loss of energy
If conventional impedance matching is used, then reflected power can be reduced, but the process requires multiple iterations
Solution Approach 1:
The system implements a feedback mechanism where the controller continuously senses RF signal parameters (voltage, current, forward power, reverse power) at multiple states within each pulse cycle. Based on this feedback and the calculated virtual admittance, the controller adjusts capacitance values to optimize impedance matching. This feedback approach minimizes reflected power while achieving rapid convergence in fewer iterations, improving overall matching efficiency.
Solution Approach 2:
The controller performs preliminary calculation of virtual admittance based on sensed parameters before executing impedance matching adjustments. By pre-calculating the optimal capacitance values rather than iterating through multiple adjustment cycles, the system reduces reflected power more quickly and improves productivity by requiring fewer iterations to achieve optimal matching.
Data Source
AI summary
An impedance matching network including a mixing module. The mixing module receives a plurality admittances based upon at least one parameter sensed from an output which generated by an RF generator. The output signal is a pulsed RF signal having a plurality of states for each pulse and the plurality of admittances correspond to the plurality states. The mixing module generates a virtual admittance determined in accordance with the plurality of admittances adjusted by a gain. The impedance matching module receives the virtual admittance and generates a command to adjust a capacitance of the impedance matching network or a command to adjust a frequency of the output signal in accordance with the virtual admittance.