Millimeter-Wave Dual-Frequency Transformer-based Rectifier.

This paper presents an mm-wave dual-frequency transformer-based rectifier for wirelessly powered IoT transponders. The dual-frequency feature not only enlarges the system capacity but also enables frequency band selection to optimize the wirelessly powered range. Meanwhile, the rectifiers’ sensitivity plays a vital role in determining the transponders’ operating distance. This paper proposed a three-stage transformer-based differential rectifier to improve the sensitivity. The proposed rectifier incorporates a vertical integration transformer, enabling stage-cascading, inductor peaking, and dual-frequency matching simultaneously while maintaining a compact size. Moreover, the inclusion of a bulk-drain-connected transistor further improves the rectifier’s efficiency and sensitivity. In this combination, the three-stage transformer-based rectifier achieves high sensitivity at both two bands. The overall sensitivity over the two operational ranges of 38 - 40 GHz and 57 - 64 GHz is below -5 dBm. The work achieves a peak sensitivity of -7.8 dBm at 40 GHz for 1 V output voltage.