A 2W, 5MHz, PCB-integration compatible 2.64cm3 regulated and isolated power supply for gate driver

This paper presents an isolated power supply unit for high-side gate driver. It generates a bipolar voltage level (+15V/-5V) and an auxiliary voltage level of +5V. The LLC topology is used at fixed frequency of 5MHz. A voltage control based on switched resonant tank is used to compensate voltage drops in the converter at high load currents. This new control strategy allows using a simple feedback loop where isolation is performed by a control transformer which is integrated with the main power transformer. The paper thus demonstrates a custom concentric planar dual transformer. Its magnetic material is made with molded ferrite/epoxy composite. The magnetic material is formed in situ with a low-temperature PCB-compatible process. The other components of the converter are off-the-shelf discrete components. The supply is implemented with GaN MOSFETs that allow higher efficiency and better output voltage control than Si devices at high switching frequency. The power supply is built as a stack of 3 PCBs, has a power density of 0.76W/cm
³
(12.45W/In
³
), and is intended to be part of the design of highly integrated PCB-based converters.