Design of an Ultra-Compact RF Rectifier for Enhanced Efficiency in Biotelemetry Wireless Power Systems

This paper presents a unique design for a high efficiency, ultra-compact RF rectifier. The rectifier incorporates a two-branch cell structure denoted as C1 and C2. These branches are integrated with a meandered line network (ML1 and ML2) for biomedical implants. The C1 structure includes a radial stub, while a series inductor is added to C1 and C2 for improved performance. The proposed rectifier is optimized to enhance power transfer efficiency over a frequency range of 1.28 to 1.52 GHz, making it particularly suitable for wireless power transfer in biomedical implants. Simulation results demonstrate a peak RF-to-DC power conversion efficiency (PCE) of 77.80% at an input power (P<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in</inf>) of 4 dBm. Additionally, the design maintains RF-to-DC conversion efficiencies exceeding 25% at P<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in</inf> levels of -20 dBm, underscoring its effectiveness in low-power conditions. Fabricated on an RT/Duroid substrate, the rectifier achieves a compact footprint of 7.8 mm × 9.3 mm and utilizes a single-series diode (SSrd) configuration. A sequential matching technique is implemented to achieve efficient performance over the desired frequency spectrum, ensuring a wide impedance bandwidth. This study highlights the potential of the proposed rectifier for wireless power transfer applications in biomedical implants, particularly in scenarios requiring the efficient utilization of ambient energy.