Flexible RF to DC Converter for Wireless Power Transfer in NFC and Biomedical Systems

To facilitate the versatile use of flexible energy harvesters, this work discusses the design and characterization of a novel radio frequency (RF) to DC converter built in indium gallium zinc oxide (IGZO) thin film transistor (TFT) technology, developed to meet the energy requirements of near-field communication (NFC) and biomedical applications. The design uses a hybrid topology that combines the efficiency of a cross-coupled converter with the voltage-enhancing capabilities of Dickson charge pumps. This converter is designed to address the challenges of variable RF environments because of its dynamic adjustment technique involving self-biasing resistors and gate voltage-boosting capacitors. The circuit is implemented in a 600 nm TFT technology, and post-layout simulations verify that the circuit can achieve a peak power conversion efficiency (PCE) of 41.5 % at a load resistance of 906 kΩ and exhibiting sensitivity levels as low as −20 dBm. The compact area of 0.0127 mm2 gives this circuit the potential for integration into disposable NFC tags and single-use biomedical devices where efficiency, size, and cost are key factors.