IEEE Trans Biomed Circuits Syst. 2022 Aug;16(4):651-663. doi: 10.1109/TBCAS.2022.3192248. Epub 2022 Oct 12.
This paper presents a hybrid load-shift keying (LSK) modulation for a load-insensitive back telemetry system to realize near-constant voltage changes in a primary coil (L) against a wide range of load variations. The hybrid-LSK-enabled full-wave rectifier enables the sequential combination of open- and short-coil functions for hybrid-LSK modulation in addition to wireless power conversion operation. Load-insensitive L voltage changes can be demodulated using the proposed slope- based demodulator, which utilizes the threshold slope of L voltage changes over the back data pulse width, enabling robust data recovery regardless of the load conditions. The 0.56-mm 0.18-μm standard CMOS hybrid-LSK prototype demonstrated that the variation of L voltage changes could be minimized to 60 mV under load changes between 50 Ω and 50 kΩ at coil separation distance of 10 mm, achieving 88.2% reduction compared to the conventional short-coil LSK with 510 mV variation. The proposed back telemetry system also achieved a bit error rate (BER) of < 9.1 × 10 under load ranges from 50 Ω to 50 kΩ and data rate of 1 Mbps, ensuring reliable back data recovery against load variations.
本文提出了一种混合负载移相键控（LSK）调制方法，用于负载不敏感后向遥测系统，以实现初级线圈（L）在宽负载变化范围内的近恒压变化。混合-LSK 使能全波整流器除了无线功率转换操作外，还可以实现开线圈和短线圈功能的顺序组合，用于混合-LSK 调制。使用基于斜率的解调器可以解调负载不敏感的 L 电压变化，该解调器利用 L 电压变化在回传数据脉冲宽度上的阈值斜率，无论负载条件如何，都能实现稳健的数据恢复。0.56mm 0.18-μm 标准 CMOS 混合-LSK 原型演示了在 10mm 线圈间隔距离下，负载在 50Ω 到 50kΩ 之间变化时，L 电压变化可以最小化到 60mV，与传统的短线圈 LSK 相比，变化幅度降低了 88.2%，后者的变化幅度为 510mV。所提出的后向遥测系统还在负载范围从 50Ω 到 50kΩ 和数据速率为 1Mbps 的情况下实现了误码率（BER）<9.1×10，确保了可靠的数据恢复，不受负载变化的影响。
