This chapter discusses the design considerations and the state-of-the-art designs of CMOS rectifiers for wireless power receivers. First, the forward current conduction capability and the reverse leakage current of on-chip passive diodes are investigated and compared. Next, comparator-based active rectifiers for near-field WPT solutions are discussed and demonstrated with a couple of design examples. Moreover, a near-optimal adaptive on-and off-delay compensation technique is introduced. Other rectifier topologies, such as the delay-locked-loop (DLL) based rectifier and the threshold-voltage compensated rectifier, are also discussed. In addition, rectifiers for RF energy harvesting for far-field WPT are discussed as well.