A 13.56-MHz Wireless Power and Data Transfer System With Current-Modulated Energy-Reuse Back Telemetry and Energy-Adaptive Voltage Regulation

Wireless power/data transfer (WPDT) through an inductive link has been an essential technique in a wide range of applications, especially for implantable medical devices (IMD), which require high power efficiency for safe operation and high data rate for continuous telemetry. This article proposes an efficient WPDT system with current-modulated energy-reuse back telemetry (ER-BT), which can induce instantaneous changes of load impedance at Rx for BT data rate up to 1 Mb/s, while reusing BT current to supply the load, improving the system power efficiency. The WPDT system also utilizes an energy-adaptive dual-input low-dropout regulator (LDO) to store and optimally reuse the BT energy for IMDs against data rate or load variations. The proposed system was fabricated in a 180-nm 1.8-/5-V standard CMOS process and measured with a coupled-coil inductive link operating at 13.56 MHz to provide a supply voltage of 1.8 V for IMDs. The proposed ER-BT can save the energy up to 42% during the BT operation compared to energy losses of the conventional short-coil (SC) BT when the inductive link provides the input power of 3.05 mW.