Triple band differential rectifier for RF energy harvesting applications

A triple band differential rectifier unit for RF energy harvesting applications is proposed in this paper. The rectifier is designed to operate in the frequency bands where some popular ambient RF sources like the UMTS (2.1 GHz), lower WLAN/Wi-Fi (2.4-2.48 GHz) and WiMAX (3.3-3.8 GHz) are available. A single stage Villard Voltage Doubler is utilized as the rectifier unit. Interdigital capacitors (IDC) are used instead of lumped components for the rectifier design in order to provide more reliability to the resultant circuit. An impedance matching unit consisting of distributed microstrip lines is also designed in order to ensure maximum power transfer between the antenna and the rectifier unit in the desired frequency bands. The impedance matching section and the rectifier unit is simulated using the Agilent ADS software. The designed rectifier unit is then fabricated and tested in order to check the validity of the design. A maximum voltage of 5.53V is measured for an input power of 14 dBm, whereas a peak RF-to-DC conversion efficiency of 42% is achieved for the same input power.