Design and realization of highly integrated isolated DC/DC micro-converter

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). It is based on the 3D integration of several elementary silicon dies in which have been integrated essential components such as the inverter, the rectifier, the HF transformer, the input and output capacitors and the output inductor. The paper deals with the silicon integration of all these elements, the presentation of our work being related with the state of the art. Then it focuses on a global estimation of the whole converter functional performances 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 mum) and have been optimized to operate at high frequency (1 MHz) in order to reduce the size of passive devices. We have integrated monolithically all is necessary for this function. The transformer as well as the inductor and the capacitors are also integrated on separate silicon dies. Their integration is discussed as well as their design and practical characterization. Based on all these pieces, 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.