This letter presents a 50∼60 GHz fully integrated 3-stage rectifier with bulk voltage bias for threshold voltage modulation in a 65-nm CMOS technology, which can be integrated in a mm-wave hybrid rectifier structure as the main rectifier. In this letter, the new technique of bulk voltage bias is proposed and implemented. In this method, the threshold voltage of MOSFETs in the main rectifier is modulated by biasing their bulk voltage, which improves the rectifier sensitivity and efficiency. Compared to the inductor peaking method  or local threshold voltage modulation technique  in CMOS technology, the circuit proposed in this letter achieves better sensitivity and efficiency while maintaining a compact size. The work achieves −10 dBm input sensitivity at 52 GHz with 1 V DC output voltage. The maximum efficiency at 52 GHz is 13%. The overall sensitivity over the 50∼60 GHz band is better than −5 dBm.