A 1.5 kW Radio-Frequency Tunable Matching Network Based on Phase-Switched Impedance Modulation

Anas Al Bastami,David Otten,Duy T. Nguyen,Aaron Radomski,Alexander Jurkov,David J. Perreault

doi:10.1109/ojpel.2020.2987782

Anas Al Bastami, David Otten + Show 4 more

Open Access

https://doi.org/10.1109/ojpel.2020.2987782

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Abstract

Dynamically-tunable impedance matching is a key feature in numerous radio-frequency (RF) applications at high frequencies (10 s of MHz) and power levels (100s–1000 s of Watts and above). This work develops techniques that enable the design of high power tunable matching networks (TMN) that can be tuned orders of magnitude faster than with conventional tunable impedance matching techniques, while realizing the high power levels required for many industrial applications. This is achieved by leveraging an emerging technique – known as phase-switched impedance modulation (PSIM), which involves switching passive elements at the rf operating frequency – that has previously been demonstrated at rf frequencies at up to a few hundred Watts. In this paper, we develop design approaches that enable it to be practically used at up to many kilowatts of power at frequencies in the 10 s of MHz. A detailed analysis of the factors affecting the losses as well as the tradeoffs of a basic PSIM-based element is provided. Furthermore, it is shown how incorporating additional stages to the PSIM-based element, including impedance scaling and / or the addition of series or shunt passive elements, influences the losses and enables the efficient processing of high power levels given the limitations of available switches. A PSIM-based TMN that matches load impedances to 50 $\,\Omega$ and delivers up to 1.5 kW of power at frequencies centered around 13.56 MHz is implemented and tested over a load impedance range suitable for various industrial plasma processes.

Highlights

A wide range of existing and emerging applications require the delivery of radio-frequency power into widely-varying loads at power levels up to several kilowatts and beyond
This paper further develops this technique, termed phaseswitched impedance modulation (PSIM), to enable the design of tunable matching network (TMN) that can efficiently process high power levels at high frequencies (10 s of MHz) with extremely fast modulation bandwidth, such that it can address the needs of high-power applications such as industrial plasma processing
While a voltage scaling factor of 2 is not alone sufficient to bring the peak voltages down to acceptable levels, it provides an acceptable tradeoff in resulting circuit component values, transformer size, and complexity; we describe an addtional technique used for reducing the phase-switched impedance modulation (PSIM) switch voltage in the subsection on the PSIM switch module

Summary

Introduction

A wide range of existing and emerging applications require the delivery of radio-frequency (rf) power into widely-varying loads at power levels up to several kilowatts and beyond. An important feature revealed by the equations is that the dependence of loss on Ceff/C0 is superlinear, and it is generally desirable to select TMN topologies that achieve the required impedance match with the lowest shunt PSIM capacitance modulation possible.

Results

Conclusion