I. Introduction
Piezo power transducers (PZT) ranging from kHz to MHz have been wildly used in industries, medicine and military field. In recent years, the class D topologies, such as a half-bridge power diver have been successfully applied to drive PZT devices with less energy loss [1–3]. But some problems bought by class D power circuit, including harmonics, voltage overshoots and Electro-Magnetic Interference actually need to pay more attentions in specific applications to improve the circuit safety and efficiency. On the other hand, since the operating frequency of these drivers depends on the matching resonant network and PZT parameters that are sensitive to environmental temperature and surrounding load, the operating frequency of diver always vary significantly [4]. A number of control integrated circuit are employed to ensure zero-voltage switching (ZVS) in all load conditions. However, at high frequency, gate driver chips still struggle with providing the gate driver signal [5–6].