Near-field inductively coupled wireless power transfer (WPT) system has been extensively utilized for brain implant applications. Still, the efficient and reliable delivery of power is challenging as the received power varies due to different variabilities between the transmitter (TX) and the receiver (RX) coils. A closed-loop adaptive control system utilizing load shift keying, designed in the 0.5 µm standard CMOS process for providing the required power to the implant load compensating for these discrepancies is proposed in this paper. Both the proposed TX and the RX coils are fabricated using FR4 substrate having the dimensions of 10 × 10 mm and 5 × 5 mm, respectively. By changing the supply voltage of the power amplifier, this adaptive closed-loop system regulates the transmitted power to deliver 5.83 mW of power to the load, which is the approximate mid-point of the threshold window. The system achieves power transfer efficiencies of 9% and 8% at 8 mm distance through the air and the tissue media, respectively. Preliminary results show that the miniaturized WPT module with the feedback-loop achieves 8% and 3% of efficiency improvement for 8 mm distance between the TX and the RX coils, compared to the open-loop counterparts.

近场感应耦合无线电力传输（WPT）系统已被广泛用于脑植入应用。但是，由于接收器的功率由于发射器（TX）线圈和接收器（RX）线圈之间的变化而变化，因此有效而可靠的功率传递仍然具有挑战性。本文提出了一种利用负载移位键控的闭环自适应控制系统，该系统以0.5 µm标准CMOS工艺设计，可为植入物负载提供所需的功率，以补偿这些差异。建议的TX和RX线圈均使用尺寸分别为10×10 mm和5×5 mm的FR4基板制造。通过更改功率放大器的电源电压，该自适应闭环系统调节发射功率，以向负载提供5.83 mW的功率，这是阈值窗口的近似中点。该系统在通过空气和组织介质的8毫米距离处分别达到9％和8％的功率传输效率。初步结果表明，与开环线圈相比，带有反馈环的小型WPT模块在TX和RX线圈之间的距离为8 mm时，效率提高了8％和3％。