A digital reverse current self-calibration technique in 90% high efficiency rectified power supply for near field communication through magnetic field induction

It is crucial in near field communication (NFC) controllers for power source transferred from mutual induction of coils when the devices are battery-off. NFC devices can be operated at the condition of low battery or even battery-off due to the requirement of payment any time. Thus, the proposed wireless power transfer (WPT) power supply can have high efficiency due to the remove of reverse leakage current by the digital reverse current self-calibration (DRCS). NFC standards including A, B, and F can be continuously supplied by the WPT supply system. The WPT power supply with the DRCS technique was fabricated in 0.25μm CMOS process can rectify AC source from induction of magnetic field to unregulated DC voltage source and to supply power the NFC controller through low dropout regulator (LDR). Moreover, test chip achieves as high as 92% voltage conversion ratio and 89.4 % power conversion efficiency (PCE) due to reduction of unnecessary current loss.