A smart card CMOS circuit with magnetic power and communication interface

On-chip magnetic interface provides power supply and communication for a chip dedicated to contactless smart card applications. Smart cards equipped with a chip, instead of a magnetic ribbon, are becoming widely used due to the reliability at system level. Contactless solutions present advantages: reduced card cost (no bonding), and improved system reliability due to the absence of electrical contacts between card and terminal. Implementing an on-chip coil to eliminate pads results in increased chip area. Economic estimates show an area less than 4mm2 seems to represent a good challenge for this approach. To achieve good power transfer between terminal antenna and on-chip coil, it is necessary to reduce the distance between the two antennas (typically a few mm), not difficult in a smart card environment. For economic reasons, the work uses a standard industrial CMOS process, with no additional process steps.