Iterative Learning Control for Impedance Matching Network

Impedance matching circuits are used in plasma processing systems to adjust a complex impedance of plasma chamber to standardized value $- 50 \Omega$. However, this unusual application introduces several challenges for impedance matching circuit, like: wide changes of load impedance related to plasma ignition or changes of load impedance in accordance to power delivered to the vacuum chamber. On top of that, there is a distinct drive to reduce time required to reach nominal VSWR to lowest possible value. Thus, to address this issue a proposal of Iterative Learning Control (ILC) algorithm for impedance matching circuit was introduced.