Signal transmission for an isolated gate driver using capacitive coupling technique

Resonant converter is widely used due to its high efficiency when carefully designed, including the tank circuit. Tuning the tank circuit is design challenging. In this paper signal isolation in the AC switch driver is presented to implement an auto-tuning system that uses synchronous switched capacitor to control the resonant frequency of the tank circuit of a half-bridge voltage fed resonant converter to power HIFU. Capacitive coupling is proposed as signal isolation instead of classical technique due to compatibility with MRI regulations used in its vicinity, avoiding bulky magnetic components. The proposed circuit works under 5V voltage and consumes 1.45mW power. With input signal frequency of 1MHz and a carrier frequency of 100MHz, the observed output signal delay is only 10ns, i.e. 1% of the signal period. The proposed circuit is designed and simulated in a CMOS 0.35μm technology. Performances such as signal delay and power consumption were studied under varying carrier frequencies to evaluate the proposed circuit.