A 13.56 MHz Time-Division Wireless Power and Data Transfer System

This contribution presents a Time-Division Simultaneous Wireless Information and Power Transfer (SWIPT) system operating at 13.56 MHz, specifically developed for IoT nodes that require low data rates. The system periodically alternates between Wireless Power Transfer (WPT) and Near Field Communication (NFC), charging the supercapacitors of the node and retrieving data from the sensor. The system is firstly presented in its two subsystems: NFC and WPT with their own couple of coils. Also, the TDD (Time-Division Duplexing) concept is explained, and applied to the system, with a square wave at a frequency of 0.1 Hz, and an 80 percent duty cycle is used to alternate between NFC and WPT. Then, experimental results are shown using the developed prototype: the NFC system shows a 0.8 Kbit/s data rate, and the ability to transfer data multiple times per cycle drawing 50 mA of current at 5 V on the tag's side; the WPT system is able to charge the supercapacitors with a steady 130-150 mA current, well above the 50mA requirement of the NFC tag.