Micromachined CMOS ICs for Wireless Charging Applications

This proposal is aimed to solve the bulky inductors/coils problem of a wireless charging system on a chip by utilizing micromachining techniques. The present wireless charger standard (e.g. Qi standard) uses lower RF frequency, such as 13.56MHz, to transmit power wirelessly, which requires very large inductors with high quality factors that cannot be integrated in CMOS ICs. This issue has prohibited wireless power transfer system from further miniaturization significantly. Although there are papers trying to solve this problem by using post-IC processing, very few (or none) demonstration has been done in standard CMOS technology. In this project we will consult the prior micromachining techniques and use it to a CMOS wireless power transfer IC. The adopted wireless charging system architecture includes wireless power coupling coils, rectifier, regulator and battery charger. The ac signal is converted to dc by a rectifier, and then stabilized by a regulator, finally entered to a three-mode (trickle charging / constant current / constant voltage) battery charging circuit. After these circuits are taped out and fabricated by foundry, we will use post-IC processing, such as substrate thinning/removal, metal thickening, and magnetic material deposition, to improve their performance. With these micromachining steps, the eddy current loss/resistive loss will be reduced and the inductance value will be increased, which help to improve the power management ICs and fulfill the concept of wireless power system on chip.

Project ID:PB10308-3591
External Project ID:MOST103-2221-E182-044-MY2