Towards Solid-State High-Power 13.56 MHz Impedance Matching Using Self-Biased SiC-MOSFET-Switched Capacitors

Radio-frequency (RF) high power (>= 500 W) plasma systems require fast, tunable impedance matching. However, conventional variable vacuum capacitor (VVC)-based networks suffer from slow mechanical tuning capabilities and wear. Solid-state solutions based on GaN/SiC MOSFETs offer a faster alternative. However, existing approaches either rely on complex multi-device structures or complex control, or are limited in power capability. This work introduces for the first time a low complexity, high-power, switched-capacitor impedance tuning network approach that uses a single MOSFET and a preceding capacitor as the basic capacitor unit. The method makes use of self-biasing the transistor via its body diode to reduce drain-source capacitance. Furthermore, a topology evaluation framework was implemented to identify networks that reduce the current and voltage stress on the transistors to an acceptable level. The first demonstrator realized using this method was measured at 500 W and 13.56 MHz, paving the way for solid-state, high-power impedance matching.