This letter presents a 38/60 GHz dual-frequency band 3-stage transformer-based inductor-peaked differential rectifier in a 40 nm CMOS technology. The rectifier is used in a wirelessly powered receiver in a monolithic IoT transponder. Its sensitivity is a bottleneck for the transponder’s range. With the dual-frequency operating function, the wirelessly powered distance could be optimized based on the selected frequency band. In this letter, a new vertical integration transformer with a compact size is proposed and implemented to achieve stage-cascading, inductor peaking, and dual-frequency matching functions simultaneously. In addition, bulk-drain-connected transistors further improve the rectifier’s efficiency and sensitivity. In this combination, the 3-stage transformer-based inductor-peaked rectifier improves sensitivity at 38 GHz and 60 GHz frequency bands. The 1-V sensitivity is -6 dBm at the 38 40 GHz frequency band and -5 dBm at 57 64 GHz frequency band. This mm-wave dual-band rectifier achieves the peak 1-V sensitivity of -7.8 dBm at 40 GHz.