A Wireless-Powered Battery-Less Electrical Stimulator With Delay-Shift Keying (DSK) Based Downlink Data Communication

This paper presents a 6.78-MHz wireless power and bidirectional data transfer system, which is intended for applications involving battery-less implantable gastric electrical stimulation (GES). The 0X/1X regulating rectifier achieves output voltage regulation without an additional DC-DC converter, thus enhancing power conversion efficiency (PCE) within the $R_{X}$ . By utilizing transmission power regulation (TPR), $T_{X}$ can adaptively adjust the transmission power according to the loading of the $R_{X}$ , reducing the power consumption during sleep mode. Moreover, this paper proposes an innovative delay-shift keying (DSK) technique for forward data transmission, enabling simultaneous voltage regulation and achieving a power conversion efficiency (PCE) of 86.1% during data transmission. Both the $T_{X}$ and the $R_{X}$ chips were fabricated in a 0.18- $\mu $ m BCD process, incorporating both 5-V and 12-V devices. During sleep mode, the consumption of the $T_{X}$ is measured at 9.24 mW, which is a 64.3% reduction compared to the same system without PA deactivation. The rectifier and charge pump achieve peak efficiencies of 86.7% and 85.8%, respectively, at a stimulus current of 6mA.