A Load-Modulated Rectifier for RF Micropower Harvesting With Start-Up Strategies

Adaptive Maximum Power Point Finding Using Direct V OC/2 Tracking Method With Microwatt Power Consumption for Energy Harvesting

“…For V HP to peak at a different value of V Ci instead of V OC /2 for transducers such as PV cells which have MPP at around 0.75V OC [4], (6) should be differentiated with respect to t and solved for τ HP by substituting the t when V Ci reaches the intended fraction of V OC into the first derivative of (6).…”

“…This occurs at the half open-circuit voltage V OC /2 of energy harvesters such as thermoelectric generators (TEG) [5], and radio frequency rectennas [6], piezoelectric energy harvesters (PEHs) which are generally weakly coupled [7], and around 0.75 to 0.8 V OC for photovoltaic (PV) cells [8]. The circuits which adopted this method can be implemented using full analog discrete component [6] or mixed-signal circuits which involve a sensing capacitor and more subsystems, for example, switch controller [3], or digital controller [4] to perform the FOCV finding algorithms and controls. The energy harvesters are momentarily disconnected from the power management module to obtain their V OC .…”

“…The energy harvesters are momentarily disconnected from the power management module to obtain their V OC . After that, the energy harvesters can be connected to a voltage divider formed by two resistors to determine the appropriate voltage ratio [6], [8] loading effect on the energy harvester and power consumption is minimized. Alternatively, the V OC is sampled using a sensing capacitor [3], [4].…”

“…Then, additional switches and capacitors are used to scale down the sampled V OC to determine the appropriate voltage ratio of the energy harvesters. The power consumption of circuit based on FOCV is usually less than the hill-climbing method, for example, 10 µW in a mixed-signal integrated circuit (IC) [3] and 5.04 µW using full analog discrete components [6]. IC with nanowatts of power consumption has been reported as well, but the input power range is limited between 25 nW and 100 µW [4].…”

A 900-2400 MHz AC-DC Rectifier Circuit for Radio Frequency Energy Harvesting

“…Therefore the Schottky diode has a limitation and the study thereafter is focusing on the usage of a CMOS. Several proposed designs had been simulated before and the results proved that the usage of CMOS have much advantages compared to Schottky diode [7][8][9][10][11][12][13]. In this paper, selected CMOS 0.13 µm technology is proposed and implemented.…”