Electrical Engineering Department, National Chung Cheng University, Min-Hsiung Chia-Yi 62102, Taiwan.
IEEE Trans Biomed Circuits Syst. 2012 Feb;6(1):28-38. doi: 10.1109/TBCAS.2011.2162409.
Inductive coupling is presented with the help of a high-efficiency Class-E power amplifier for an implantable cardiac microstimulator. The external coil inductively transmits power and data with a carrier frequency of 256 kHz into the internal coil of electronic devices inside the body. The detected cardiac signal is fed back to the external device with the same pair of coils to save on space in the telemetry device. To maintain the power reliability of the microstimulator for long-term use, two small rechargeable batteries are employed to supply voltage to the internal circuits. The power management unit, which includes radio frequency front-end circuits with battery charging and detection functions, is used for the supply control. For cardiac stimulation, a high-efficiency charge pump is also proposed in the present paper to generate a stimulated voltage of 3.2 V under a 1 V supply voltage. A phase-locked-loop (PLL)-based phase shift keying demodulator is implemented to efficiently extract the data and clock from an inductive AC signal. The circuits, with an area of 0.45 mm², are implemented in a TSMC 0.35 μm 2P4M standard CMOS process. Measurement results reveal that power can be extracted from the inductive coupling and stored in rechargeable batteries, which are controlled by the power management unit, when one of the batteries is drained. Moreover, the data and clock can be precisely recovered from the coil coupling, and a stimulated voltage of 3.2 V can be readily generated by the proposed charge-pump circuits to stimulate cardiac tissues.
采用高效率的 E 类功率放大器为植入式心脏微刺激器提供感应耦合。外部线圈以 256 kHz 的载波频率感应传输功率和数据到体内电子设备的内部线圈。检测到的心脏信号通过同一对线圈反馈到外部设备，以节省遥测设备中的空间。为了保持微刺激器的长期使用的电源可靠性，使用两个小的可充电电池为内部电路供电。电源管理单元包括具有电池充电和检测功能的射频前端电路，用于电源控制。对于心脏刺激，本文还提出了一种高效率的电荷泵，可在 1 V 电源电压下产生 3.2 V 的刺激电压。实现了基于锁相环 (PLL)的相移键控解调器，可有效地从感应交流信号中提取数据和时钟。这些电路采用 TSMC 0.35 μm 2P4M 标准 CMOS 工艺，面积为 0.45 mm²。测量结果表明，当其中一个电池耗尽时，可以通过感应耦合从外部线圈中提取电能并存储在可充电电池中，由电源管理单元进行控制。此外，可以从线圈耦合中精确地恢复数据和时钟，并且可以通过所提出的电荷泵电路产生 3.2 V 的刺激电压来刺激心脏组织。
