RF to DC micro-converter in standard CMOS process for on-chip power harvesting applications

In this paper a radio frequency (RF) to direct current (DC) voltage converter with multi-stage rectifiers is reported for micro power conversion in RF power harvesting systems. The purpose of this paper is to select an appropriate structure for the micro power-converters, operating in high frequencies. The main idea is to convert RF range sinusoidal signals to a DC voltage to produce power for the rest of the electrical circuit or a system. The reported rectifier demonstrated an efficiency of 10% at large span of frequency for input signal of 350 mV. In the presented work, an analytical and numerical study of the micro power-converters is reported for various applications. Different design parameters have been investigated for an efficient structure design including, number of MOSs, DC current of a known load, size of MOSFETs capacitors, and frequency of the operation. Consequently, optimized parameters have been reported in order to improve the RF to DC conversion efficiency. Reported circuits were designed and simulated in 180 nm twin-well CMOS process with low threshold metal-oxide semiconductor field-effect transistors (MOSFETS); this multistage rectifier occupied an area of 0.23 mm × 0.146 mm and it produced an output voltage of 2 V at its output. This output voltage can provide the supply voltage required to operate the RFID processing circuitry. Post layout simulations demonstrated that for thirteen stages of the rectifiers, the efficiency of 10% for a capacitive load of 10 pF has been achieved.