Ultrawideband Conversion Efficiency Obtained Through an Optimized Rectifier Structure for IoT Energy Harvesting

Wideband rectifiers for IoT energy harvesting have been extensively researched for decades. The main challenge in designing a wideband rectifier is achieving impedance matching for diodes across a broad frequency range. In conventional engineering practices, the circuit topology and matching network are meticulously engineered to achieve extended bandwidth. However, the input frequency bandwidth is also limited by the matching network, which generally results in an increase in the physical dimensions of this network. This paper proposes a novel parallel multistage voltage multiplier with frequency-insensitive input impedance, comparing three common rectifier diode topologies. To validate the objectivity of the proposed design methodology, a comparative analysis is conducted among three conventional rectifier diode topologies under a standardized matching network structure. This analysis assesses the stability and consistency of each topology. Leveraging this feature effectively, an uncomplicated matching network can still achieve ultra-wide bandwidth performance. A specialized model has been designed for verification. The test results show that the rectifier power conversion efficiency remains above 50% from 0.2 to 2.6 GHz, with a relative bandwidth of 171.4%. The total dimensions can be as compact as 28 × 10 mm2. When the input power is set to 12 dBm, the peak efficiency exceeds 82%.