In this paper, a multi-band RF energy harvesting circuit is designed. The output voltage and power of the system built at 900 MHz, 1800 MHz and 2450 MHz frequencies are revealed. All simulations in this paper are made using the Advance Design System (ADS) 2017 program.The load resistances that give the maximum power for each frequency are determined and the appropriate load is selected for all three frequencies. Then, the multi-stage Dickson Voltage Multiplier (DVM) from two to six stages is designed and the number of stages giving the maximum power for each frequency is determined using the selected load. L type and π type impedance matching have been applied to obtain the maximum output power in DVM design, which includes this number of stages and has two Schottky diode models (HSMS-2852).Finally, these three circuits are combined and the output voltage and efficiency of the resulting system are analyzed.