Auto tuning system for a half bridge resonant converter using a synchronous switched capacitor

In this paper, an auto tuning system that uses a variable synchronous switched capacitor for controlling the resonant frequency of the tank circuit of a half bridge voltage mode resonant converter for High intensity focused ultrasound (HIFU) applications is presented. The presented auto tuning system using a switched capacitor instead of a large inductor in the classical tuning topology. Hence, there will be no need of bulky magnetic components. which makes it naturally comply with the Magnetic Resonance Imaging (MRI) compatibility regulations. The designed circuit works under 1MHz, which is simulated in a CMOS 0.35μm technology. The required performances have been confirmed by simulation results.