The survey and development of power supply unit for passive RFID tag functioning on ultra-high frequency are presented in this paper. RFID (radio-frequency identification) is a technique of objects identification in which data, stored in radiofrequency transponders or tags, is read and wrote by means of radio signals. One of the most important parts of RFID tag providing the energy for proper operation of tag is power supply module. Power supply unit can include such cells for harvesting and provision of energy as voltage rectifiers and multipliers, voltage regulators, bias schemes and others. This work considers design features of the rectifier with voltage multiplying which is capable to provide rectified voltage of 1.2 V while input radiofrequency voltage amplitude is less than 0.7 V. The circuit functions at 2.45 GHz frequency and is designed for implementation using 90 nm CMOS technology. Comprehensive simulation of the rectifier operation with variations of determining parameters was conducted. Besides, the voltage reference for voltage regulator was also developed and simulated.