A wireless power transmission subsystem with capacitor-less high PSR LDO and thermal protection mechanism for artificial retina application

This paper presents a wireless power transmission subsystem with high power supply rejection (PSR) low dropout (LDO) regulator and thermal protection mechanism for artificial retina application. The proposed subsystem performs the functions of rectification, regulation and thermal detection. It can provide a stable DC source for implanted devices, and the subsystem only needs a small rectification capacitor. The proposed LDO achieves high PSRR performance of 46 dB at 10 MHz without any external capacitor. Moreover, the system contains the thermal protection mechanism to prevent cells from being damaged. A power controller in the system controls the received power by adjusting resonant capacitance in feedback. By controlling the received power, the system avoids receiving excessive power, enhances the power transmission efficiency, and avoids the device to be damaged by excessive heat. The proposed subsystem is to be fabricated with the TSMC 0.18 um CMOS process and occupies area of 556 um × 700 um. It achieves a high power conversion efficiency of 73 % under output voltage of 3.3 V and load current of 5 mA.