Voltage-Boosted Current-Mode Wireless Power Receiver for Directly Charging a Low-Voltage Battery in Implantable Medical Systems

A resonant current-mode receiver is studied to charge low-voltage batteries wirelessly for supplying medical implantable systems. To increase efficiency, the root-mean-square (RMS) current in the LC tank of the receiver (RX) is reduced by using a voltage-boosted current-mode (VBCM) receiver. This receiver combines the conventional current-mode receiver with a switched-capacitor converter to boost the voltage instantaneously at the switching node ( $V_X$ ) of coil. Owing to the suggested technique, the receiver directly charges a low-voltage battery while maintaining a small RMS current without using a complex voltage regulator. The receiver achieves an efficiency as high as 84.7% with a 1.1 V battery while operating at the resonant frequency ( $f_{reso}$ ) of 6.78 MHz. The power delivered to the output ( $P_{o}$ ) is in the range from 1.5 mW to 50 mW. The VBCM receiver was fabricated by 180 nm CMOS technology with a total active area of $\rm0.22 mm^2$