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This letter introduces a self-oscillating very high-frequency (VHF) class $\phi$ 2 inverter based on a free-running oscillator. The class $\phi$ 2 is a low-voltage semiconductor stress, fast-transient, single-transistor inverter topology suitable for VHF applications. With new advancements in GaN technology, the tendency to increase the switching frequency in power converters is on the rise. Switching at VHF (VHF: 30–300 MHz) allows for smaller passive components and more compact power converters. However, although GaN components are able to switch at 100 MHz and beyond, gate drivers available in the market struggle to provide the adequate switching signal at VHF. Hence, there is a need for an alternative to VHF converters using those gate drivers—self-oscillating topologies. To that end, a self-oscillating class $\phi$ 2 inverter switching at 30 MHz is presented and a design methodology is provided. A 30 MHz prototype with 30 V input voltage using a GaN Systems GS61004B is also built and tested, showing good matching between the simulation and experimental results. [ABSTRACT FROM AUTHOR]

This paper deals with the design and the implementation of an isolated and highly integrated low voltage, low power microconverter. A dual active-bridge topology is considered as a good candidate for reducing the number of passive elements. The design of a “power die” integrating power inverter legs and their driver circuits is carried out in order to benefit from the high level of integration and to reduce the amount of active components and the volume of the converter. Thus, a microconverter is built for 10 W power supply (5 V/2 A) and is operating at 1 MHz switching frequency. The measured efficiency of the converter is 88% for 6.5 W transferred power and 86% for 8.5 W transferred power without taking into account its control unit. The converter is operating in natural convection, and no cooling system is implemented. Therefore, a power density of 9.9 kW/L is achieved, which is beyond the state of the art of the conventional isolated converters whose power densities are around 1–2 kW/L at the same power level. [ABSTRACT FROM AUTHOR]

This paper deals with the design and the realization of an integrated isolated HF dc-to-dc converter for low-voltage and low-power conditioning applications (3.3 V and 1 W) including galvanic isolation. It is based on the 3-D integration of several elementary silicon dies in which essential components such as the inverter, the rectifier, the HF transformer, the input and output capacitors, and the output inductor have been integrated. The paper deals with the silicon integration of all these elements, with the presentation of our work being related with the state of the art. Then, it focuses on an estimate of the whole converter functional performance at 1-MHz switching frequency. Practical but partial implementation was carried out. The inverter and the rectifier are designed in CMOS technology (Austria Micro Systems 0.35 \mu\m) and have been optimized to operate at HF (1 MHz) to reduce the size of passive devices. We have monolithically integrated all that is necessary for this function. The transformer, as well as the inductor and the capacitors, is also integrated on separate silicon dies. Their integration is discussed, as well as their design and practical characterization. Based on a distributed construction, the overall converter efficiency is estimated in simulation based on practical characterizations. It appears that correct efficiency with a reasonable silicon surface and volume can be reached. [ABSTRACT FROM PUBLISHER]