Energy Management Circuit Research Articles

High-Performance Rotating Structure Triboelectric-Electromagnetic Hybrid Nanogenerator for Environmental Wind Energy Harvesting.

As environmental energy harvesting gains increasing importance in self-powered systems and large-scale energy demands, wind energy, as a clean, pollution-free, and renewable source, has garnered widespread attention. However, achieving efficient wind energy collection remains challenging. This study proposes a high-performance rotating structure triboelectric-electromagnetic hybrid nanogenerator designed for environmental wind energy harvesting. By optimizing the magnetic circuit design of the electromagnetic generator, the dispersed radial magnetic field is converted into a unified axial magnetic field, enabling efficient power generation with only a single annular coil, thereby simplifying the generator design and reducing manufacturing and maintenance costs. Additionally, a triboelectric nanogenerator design with soft contact friction between polycarbonate (PC) fur and fluorinated ethylene propylene (FEP) film was implemented, optimizing the spacing between the electrode and friction layers, thus enhancing output performance and device durability. Furthermore, we simulated and experimentally tested the output waveform of the designed hybrid generator structure, with the results showing a high degree of similarity, further validating the rationality of the device design and providing guidance for structural optimization. Subsequently, we achieved efficient energy storage using an energy management circuit (EMC). With the integration of the EMC, the generator successfully powered a Bluetooth temperature and humidity sensor at a wind speed of 10 m/s, achieving wireless transmission, and demonstrating its potential application in traffic signal systems and other natural environmental systems. This research provides an important reference for further exploration of novel wind energy harvesting technologies.

High‐Gain Boost Converter Based Energy Harvesting Method for the Ultra‐Low Voltage Difference of HVDC Transmission Line

ABSTRACTOnline monitoring sensors are crucial for ensuring the long‐term stable operation of high‐voltage direct current (HVDC) transmission systems. However, ensuring a sustainable and reliable energy supply for these sensors in the HVDC transmission line is extremely challenging. Energy harvesting is an efficient solution to meet the energy supply needs of self‐powered online monitoring sensors. This work proposes a novel method for harvesting energy from the ultra‐low voltage difference of HVDC transmission line using a high‐gain boost converter. Firstly, the structure of the energy harvesting system is proposed. Then, the mechanism by which the gain of the boost converter is easily affected by parasitic parameters of the circuit and device under ultra‐low input voltage is analyzed. A method for automatically stabilizing the output voltage of the boost converter using a post‐stage energy management circuit is proposed. This method avoids the use of closed‐loop control circuits, which would otherwise increase losses. Finally, the boost converter with high gain is designed to elevate the ultra‐low voltage difference to a higher voltage, providing sufficient power for the online monitoring sensors. The effectiveness of the proposed method has been verified through simulations and experiments, demonstrating that the energy harvesting system can extract energy from a voltage difference as low as 35 mV. Additionally, the system can produce a stable output power of up to 128 mW when the voltage difference is 100 mV.

A High-Efficiency Piezoelectric Energy Harvesting and Management Circuit Based on Full-Bridge Rectification

This paper presents a high-efficiency piezoelectric energy harvesting and management circuit utilizing a full-bridge rectifier (FBR) designed for powering wireless sensor nodes. The circuit comprises a rectifier bridge, a fully CMOS-based reference source, and an energy management system. The rectifier bridge uses a PMOS cross-coupled structure to greatly reduce the conduction voltage drop. The CMOS reference source provides the necessary reference voltage and current. The energy management system delivers a stable 1.8 V to the load and controls its operation in intermittent bursts. Fabricated with a 110 nm CMOS process, the circuit occupies an area of 0.6 mm2, and is housed in a QFN32 package. Test results indicate that under 40 Hz frequency and 4 g acceleration vibrations, the chip’s energy extraction power reaches 234 μW, with the load operating every 3 s at a supply voltage of 1.8 V. Thus, this FBR interface circuit efficiently harnesses the energy output from the piezoelectric energy harvester.

Self-Supplying Photovoltaic-Hygroelectric Coupling System Powering Internet of Things Sensors.

The rapid advancement in the Internet of Things (IoT) has prompted a proliferation of sensor applications with increasing focus on harnessing environmental energy sources for powering these sensors. However, owing to the variability inherent in climatic and geographic conditions, a singular approach to environmental energy harvesting often fails to deliver sustainable and reliable power. Hygroelectric technology, leveraging the electrical coupling between nanostructured materials and water to convert moisture-derived energy into electricity, complements the advantages of light energy collection technology. In this study, an ion diode moisture-based power generation array was fabricated to yield an open-circuit voltage of 8 V and a short-circuit current of 3 mA under an 86.9% relative humidity (RH). Subsequently, integration of a photovoltaic module with the hygroelectric generator assembly via an energy management circuit augmented the system's overall power generation, manifesting a remarkable 1150% increase over the original moisture-based power generation configuration. Furthermore, the incorporation of such a hybridized system bolstered the operational efficiency, extending the duration of continuous power supply cycles by up to 78.2% in comparison with the control group with no moisture-derived energy input. This pioneering endeavor unveils a novel light-moisture coupling energy-harvesting paradigm tailored for sustaining uninterrupted power provision in wireless sensor network nodes, and the harvesting of one energy source is not affected by the other energy source at all. With its inherent adaptability, this approach holds promise for deployment in outdoor environments characterized by low illumination levels and high humidity, presenting a versatile solution to address sensor powering challenges.

Steady Output Triboelectric-Electromagnetic Hybrid Generator with Variable Drag Turbine Blades for Natural Wind Energy Harvesting.

In recent years, the triboelectric-electromagnetic hybrid generator (TEHG) has been widely studied. However, the problems of unsteady output and high starting wind speed of traditional TEHG in the wind energy environment have not been effectively solved. This work introduces an innovative solution in the form of a steady output triboelectric-electromagnetic hybrid generator (SO-TEHG) with variable drag turbine blades. The SO-TEHG integrates the energy management circuit to output steady electric energy under random wind conditions. In addition, the integration of variable drag turbine blades with the triboelectric nanogenerator (TENG) reduces the wind speed threshold required for SO-TEHG activation. In comparison to the traditional turbine blades, which necessitate a minimum wind speed of 3 m/s, the SO-TEHG's innovative design allows it to commence power generation at a lower 2 m/s wind speed, producing an additional output of 50 V. This enhanced starting capability in mild breezes positions the SO-TEHG as an ideal power source for applications. In practical farmland settings, experimental results conclusively demonstrate the SO-TEHG's ability to successfully activate soil hygrothermographs and hydrogen sensors. As a steady power source driven by gentle winds, the SO-TEHG holds tremendous promise for advancing smart agriculture.

Dual-mode electromagnetic-triboelectric-piezoelectric multifunctional self-charging energy system for efficient capture of kinetic energy

This study presents an innovative dual-mode electromagnetic-triboelectric-piezoelectric multifunctional self-charging energy system (MS-CES) that integrates two different operating modes of electromagnetic generators for contact-separation (CS-EMG) and non-contact (NC-EMG), as well as a triboelectric nanogenerator (TENG) and a piezoelectric nanogenerator (PENG). The system has an energy management circuit that efficiently captures and converts kinetic energy from the environment. We investigate the output performance of each unit of the MS-CES under different vibration frequencies and amplitudes. The units work together through a compact mechanical structure design to achieve high voltage output while shortening charging time based on improved space utilization, thus gaining more efficient energy storage. Polyacrylonitrile (PAN) powder and barium titanate (BTO) composite nanofibre membrane (PAN/BTO) as PENG material further enhances the system's output performance. The system provides a continuous power source for the vibration sensors. It enables human-computer interaction with mobile phones and computers via Bluetooth modules, enabling real-time monitoring and analysis of vibration parameters. Furthermore, we have validated the feasibility of using the MS-CES to power a noninvasive vagus nerve stimulation device, providing new technological means for monitoring and treatment in the medical field.

Earthworm-Inspired Ultra-Durable Sliding Triboelectric Nanogenerator with Bionic Self-Replenishing Lubricating Property for Wind Energy Harvesting and Self-Powered Intelligent Sports Monitoring.

Triboelectric nanogenerators (TENGs), a promising strategy for harvesting distributed low-quality power sources, face inevitable bottlenecks regarding long-term abrasion and poor durability. Herein, both issues are addressed by selecting an earthworm-inspired self-replenishing bionic film (ERB) as the tribo-material of sliding-freestanding TENGs (SF-TENGs), it consists of an interconnected 3D porous network structure capable of storing and releasing lubricant under cyclic mechanical stimuli. Thanks to the superiority of self-replenishing property, there is no need for periodic replenishment and accurate content control of lubricant over the interfacial-lubricating SF-TENGs based on dense tribo-layers. Additionally, an SF-TENG based on ERB film (ERB-TENG) demonstrates remarkable output stability with only a slight attenuation of 1% after continuous operation for 100000 cycles. Moreover, the ERB-TENG displays a distinguished anti-wear property, exhibiting no distinct abrasion with an ultra-low coefficient of friction (0.077) and maintaining output stability over a prolonged period of 35 days. Furthermore, integration with an energy management circuit enables the ERB-TENG to achieve a 39-fold boost in charging speed. This work proposes a creative approach to enhance the durability and extend the lifespan of TENG devices, which is also successfully applied to wind energy harvesting and intelligent sports monitoring.

Power improvement of triboelectric nanogenerator by morphological transformation strategy for harvesting irregular wave energy

Wave is inherently characterized by disorder and randomness, which is a great challenge for the conventional wave-based triboelectric nanogenerator (W-TENG) and necessitates conducting adaptability research on the device. Therefore, we proposed a morphological transformation strategy, that is, W-TENG can actively transform the motion patterns of self-structure to accommodate the variations in waves and achieve power improvement. And a morphological transformation TENG (MT-TENG) with multi-mode operation is developed for harvesting irregular wave energy. Furthermore, the disorder wave motion is transformed into a bidirectional continuous rotation of power generation units, which realizes the continuous waveform output. Experimental results demonstrate that the wave power grows by 9.22 times with frequency increase, and the device's performance increases by 114.136 times utilizing this strategy. MT-TENG can output 39.67 mA through the energy management circuit (EMC) and a peak power density of 30.62 W/m3 under the wave excitation of 1.1 Hz. Finally, the self-powered environmental monitoring system is constructed, which can illuminate ten 30 W LEDs in series and provide a continuous energy supply to the wireless sensor module. This work presents a research paradigm for the design of wave-environment adaptability, holding significant implications for improving performance and constructing self-powered sensing systems.

A Three-Transistor Energy Management Circuit for Energy-Harvesting-Powered IoT Devices

Energy harvesting (EH) provides a promising solution for powering distributed Internet of Things (IoT) devices. Due to the low-level and sporadic ambient energy supply, an EH-powered device should operate in an intermittent and energy-driven mode. Commercial voltage supervisors were not optimized for the EH scenario, making it difficult to satisfy all new demands. The conventional energy management (EM) circuit has a risk of locking up during the turn-on transient; therefore, it might fail to power the IoT load device. Previous technologies have used a relatively large circuit to solve this problem. In this paper, a concise discrete three-transistor energy management circuit (3T-EM) is proposed. It can track stored energy, switch on/off to the load device, and provide a regulated voltage output. These key functions are realized by utilizing a minimum number of components; therefore, power consumption and manufacturing cost are largely cut. The voltage thresholds and minimum input current are theoretically derived. In experiments, the on/off thresholds can be adjusted accurately, as predicted by the theory. The 3T-EM circuit can ensure the correct operation when the input current is as low as 0.4 μA. Control experiments also prove the effectiveness and performance of the 3T-EM circuit. The proposed 3T-EM circuit shows the characteristics of low cost, low power, inherent regulation, high voltage rating, and good predictability. It is a good candidate to perform the EM task in widely distributed EH-powered IoT devices.

High Performance Rotary‐Structured Triboelectric‐Electromagnetic Hybrid Nanogenerator for Ocean Wind Energy Harvesting

AbstractModern ship is an important transportation and even military equipment on the ocean, which has ubiquitous ocean wind energy with high‐speed and stable wind direction. However, much higher‐speed wind energy during the movement of the ship is often abandoned. Triboelectric nanogenerator (TENG) that can generate electrical energy by scavenging ambient mechanical energy is one of the emerging energy harvesting technologies. By coupling the TENG and electromagnetic generators (EMG), a high‐performance rotary‐structured triboelectric‐electromagnetic hybrid nanogenerator (RS‐HG) is designed in this study. By introducing a matched inductor in the paired energy management circuit (EMC), the charging efficiency of RS‐TENG can be effectively enhanced by 15 times compared to that without EMC. At a simulated wind speed of 15 m s−1, the peak power of lateral TENG (L‐TENG), top TENG (T‐TENG) and EMG are 7.54, 7.85, and 22.5 mW, respectively. The demonstrated RS‐HG comprising two RS‐TENGs and one EMG can readily charge a 1 mF capacitor to 8 V within 15 s under the wind speed of 15 m s−1 and continuously power the electronic devices. Moreover, the RS‐HG can also successfully charge a smartphone through the step‐down and voltage stabilization module to further expand its application scenarios. The applications of powering portable electronics reveal the huge prospects of hybrid nanogenerators in energy harvesting and self‐powered environmental monitoring during navigation.

Energy Harvesting and Acceleration Measuring Based on Time-Division Multiplexing Operation of a Single Piezoelectric Transducer

This letter presents a novel approach called energy harvesting and acceleration measuring (EHAM) using a single piezoelectric (PZT) transducer. The EH subsystem is a synchronous electric charge extraction (SECE) interface combining with an energy management circuit, which can harvest energy from PZT. The AM subsystem is for measuring acceleration-related signals. A time-division multiplexing strategy is employed in the EHAM system, where vibration energy is harvested during one period and vibration acceleration is measured in another period, and the harvested energy also powers the AM circuit. The prototyped EHAM system is implemented based on discrete components and tested with a conventional cantilever-based PZT harvester. Experimental results show that the EHAM system can perform EH and AM operations in a time-division multiplexing way. The EH circuit can harvest 1.76 mJ energy during 22 s with a PZT open-circuit voltage of 6 V. The AM circuit can measure accelerations with an accuracy of 95% under the mechanical resonance condition. The EHAM solution can be a candidate for self-powered acceleration measurement.

High Areal Capacity and Long Cycle Life Flexible Mild Quasi‐Solid‐State Ag–Zn Battery with Dendrite‐Free Anode

Silver‐zinc (Ag–Zn) batteries are a promising battery system for flexible electronics owing to their high safety, high energy density, and stable output voltage. However, poor cycling performance, low areal capacity, and inferior flexibility limit the practical application of Ag–Zn batteries. Herein, we develop a flexible quasi‐solid‐state Ag–Zn battery system with superior performance by using mild electrolyte and binder‐free electrodes. Copper foam current collector is introduced to impede the growth of Zn dendrite, and the structure of Ag cathode is engineered by electrodeposition and chloridization process to improve the areal capacity. This novel battery demonstrates a remarkable cycle retention of 90% for 200 cycles at 3 mA cm−2. More importantly, this binder‐free battery can afford a high capacity of 3.5 mAh cm−2 at 3 mA cm−2, an outstanding power density of 2.42 mW cm−2, and a maximum energy density of 3.4 mWh cm−2. An energy management circuit is adopted to boost the output voltage of a single battery, which can power electronic ink display and Bluetooth temperature and humidity sensor. The developed battery can even operate under the extreme conditions, such as being bent and sealed in solid ice. This work offers a path for designing electrodes and electrolyte toward high‐performance flexible Ag–Zn batteries.

Self-Powered Synchronized Switching Interface Circuit for Piezoelectric Footstep Energy Harvesting.

Piezoelectric Vibration converters are nowadays gaining importance for supplying low-powered sensor nodes and wearable electronic devices. Energy management interfaces are thereby needed to ensure voltage compatibility between the harvester element and the electric load. To improve power extraction ability, resonant interfaces such as Parallel Synchronized Switch Harvesting on Inductor (P-SSHI) have been proposed. The main challenges for designing this type of energy management circuits are to realise self-powered solutions and increase the energy efficiency and adaptability of the interface for low-power operation modes corresponding to low frequencies and irregular vibration mechanical energy sources. In this work, a novel Self-Powered (SP P-SSHI) energy management circuit is proposed which is able to harvest energy from piezoelectric converters at low frequencies and irregular chock like footstep input excitations. It has a good power extraction ability and is adaptable for different storage capacitors and loads. As a proof of concept, a piezoelectric shoe insole with six integrated parallel piezoelectric sensors (PEts) was designed and implemented to validate the performance of the energy management interface circuit. Under a vibration excitation of 1 Hz corresponding to a (moderate walking speed), the maximum reached efficiency and power of the proposed interface is 83.02% and 3.6 mW respectively for the designed insole, a 10 kΩ resistive load and a 10 μF storage capacitor. The enhanced SP-PSSHI circuit was validated to charge a 10 μF capacitor to 6 V in 3.94 s and a 1 mF capacitor to 3.2 V in 27.64 s. The proposed energy management interface has a cold start-up ability and was also validated to charge a (65 mAh, 3.1 V) maganese dioxide coin cell Lithium battery (ML 2032), demonstrating the ability of the proposed wearable piezoelectric energy harvesting system to provide an autonomous power supply for wearable wireless sensors.

A high-performance mini-generator with average power of 2 W for human motion energy harvesting and wearable electronics applications

The sustainability of power supply for mobile electronic devices is a problem that needs to be solved urgently. The energy from human motion is an optimal solution for this problem. As for the traditional energy harvesters based on electromagnetic, triboelectric, and piezoelectric induction, energy management is the largest challenge because of the low conversion efficiency and output power. In this paper, a high-efficiency and high-power energy harvester (EPEH) is presented based on the intersecting beam array structure. It can effectively harvest the pressure energy of humans under the soles at the states of walking, running, and weight-bearing walking. The EPEH does not impair the flexibility of humans compared with joint energy harvesters. The intersecting beam array structure is key component, which can magnify the compression distance in the vertical direction of 3.4 times in the horizontal direction, facilitating maximum energy harvesting within a limited height. On the other hand, the design of rolling friction structure can effectively reduce energy loss and improve energy conversion efficiency. The result shows that the maximum average output power can reach 2 W at 7 km/h. Because of the high output power, the energy management circuits and voltage regulator circuits can be derived and stable work, the energy harvested by the EPEH can be stored in the lithium battery (3.7 V, 50 mAh). Furthermore, the generated energy could supply mobile phones, smart watches, light bulbs, flashlights, children's anti-lost devices, and so on. Through the energy management circuit and voltage regulator circuit (1.5 V and 5 V), the energy conversion efficiency of the device can reach 65.2 % at a compression velocity of 2500 mm/min and a frequency of 1.25 Hz. It is of great significance for the practical application of wearable energy harvesting technology and has multiple application prospects.

Autonomous WSNs node powered by a thermal energy harvester for temperature monitoring

An autonomous wireless sensor networks (WSNs) node powered by a thermal energy harvester with MPPT is proposed in this paper for temperature monitoring. Two commercial TEG modules are used to build up the thermoelectric collector, while an energy management circuit with a DC/DC converter is employed to boost the TEG output voltage. The harvested energy is stored in a supercapacitor. The feasibility of the presented self-powered WSNs node is verified by a series of experiments with various node sleep periods and temperature differences across the thermoelectric generator (ΔT TEG). The results show that the proposed thermal energy harvester can work at its maximum power point and autonomously power a commercial WSN node when ΔT TEG is above 13.3°C and node sleep period is not less than 1.5 s. In addition, the designed self-powered WSNs node can monitor the temperature of industrial devices successfully.

High‐Efficiency Energy Management Circuit Combining Synchronized Switch Harvesting on Inductor Rectifier and Impedance Matching for Impact‐Type Piezoelectric Energy Harvester

To improve the output power of impact‐type piezoelectric energy harvesters (IPEHs), a high‐efficiency energy management circuit combining a self‐powered synchronized switch harvesting on inductor (SP‐SSHI) rectifier and an alternative impedance matching circuit is proposed. The SP‐SSHI rectifier eliminates the effect of inherent capacitance of IPEH through LC oscillation and enhances the output power. The alternative impedance matching circuit provides two optimal load resistances for different periods of IPEHs to increase the harvested power. Furthermore, to decrease the power dissipation, the proposed circuit is activated only when the output power of IPEH is sufficiently high and the SSHI is active. A control chip of the proposed circuit is designed and fabricated in a 0.18 μm complementary metal‐oxide semiconductor process. The proposed circuit is applied for a microwind IPEH, and the peak figure of merit and efficiency are 3.68 and 90.4%, at the wind speed of 1.46 m s−1, respectively. The results indicate a significant improvement in output power and harvesting efficiency of the proposed IPEH‐specialized circuit. When a flame sensor (USEQFSEA22L80) is powered by the microwind energy harvesting system, the proposed circuit increases operating time of the sensor as 4.6 times, as compared with the traditional impedance matching circuit.

Durability Improvement of Breeze‐Driven Triboelectric‐Electromagnetic Hybrid Nanogenerator by a Travel‐Controlled Approach

AbstractTriboelectric nanogenerator (TENG), as an emerging technology for distributed energy harvesting, provides a promising energy solution for self‐powered environmental monitoring. However, the abrasion of triboelectric materials lowers the output performance of TENGs, severely limiting their practical applications. Herein, a novel travel‐controlled approach, by combining a gear train and cam switch, is proposed to reduce the mechanical wear. The automatic switching between the contact and non‐contact modes can be achieved in a tunable frequency, showing excellent electrical stability by maintaining 90% of electric outputs after continuous operation for 80 h (1 920 000 cycles). Meanwhile, based on the structural optimization, the power density per unit wind speed of the travel‐controlled TENG (TC‐TENG) is doubled as compared with that of previous related works. Moreover, by integrating the triboelectric‐electromagnetic hybrid device with an energy management circuit, a self‐powered close‐looped environmental monitoring and alarming system are demonstrated. Under breezy conditions (below 3 m s−1), the system can detect the environmental information continuously and steadily, and transmit it wirelessly to a mobile device. This work renders a novel approach to reducing the wear in TENGs toward self‐powered wireless sensing systems, showing broad application prospects in distributed unmanned environmental monitoring, smart farming, and Internet of Things.

Vibration-Driven Triboelectric Nanogenerator for Vibration Attenuation and Condition Monitoring for Transmission Lines.

Vibration is an omnipresent energy source that is renewable and has the potential to cause damage to transmission lines. Harvesting harmful vibration energy can achieve vibration attenuation. Here, a vibration-driven triboelectric nanogenerator (V-TENG) with the potential for vibration attenuation is proposed as a power source for monitoring the operating condition of transmission lines. The V-TENG with structural optimization and frequency response range improvement is first discussed, indicating that it has a simple structural design with a good output performance. Then an energy management circuit is used to improve the charging efficiency of large capacitors. The vibration attenuation effect and wireless transmission system are verified in the simulation environment, benefiting from the well-designed structure and outstanding electric performance. This work demonstrates an efficient strategy for harvesting vibration energy through the TENG, which provides valuable guidance for further construction of online monitoring of transmission lines.

Pendulum-Based River Current Energy Converter for Hydrometric Monitoring Systems

Energy harvesting from flowing water is important for supplying hydrometric monitoring systems. Nevertheless, it is challenging due to the chaotic water flow in only one main direction and the relatively weak energy profile. In this paper, a novel energy harvester has been proposed, designed, and validated. The converter consists of a pendulum, a gearbox, two overrunning clutches, a spiral spring, and a generator. By coupling the kinetic energy via an oscillating mass equipped with a magnetic spring, it is possible to accommodate the power supply, electronics, and sensors with data transmission in a completely closed, encapsulated, stable housing without an interface to the outside. In addition, an energy management circuit and a battery charging circuit were developed that could be housed in the sealed enclosure. The pendulum transducer prototype was tested with the developed online hydrometric measurement station, which consists of a multi-channel data logger with a cellular modem and a tipping bucket rain gauge sensor. The overall system was successfully validated by experimental studies in a river.

An Optically Transparent Metantenna for RF Wireless Energy Harvesting

We propose a novel transparent metasurface antenna (metantenna) based on indium tin oxide (ITO) material for simultaneously achieving wireless energy harvesting (WEH) at radio frequency (RF) bands and efficient transmission of visible light. We adopt the design method of aperture-coupled metantenna to realize broadband and low-profile RF WEH. Then, we replace the conventional opaque metal material with an ITO coating with a sheet impedance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1~\Omega $ </tex-math></inline-formula> /sq to achieve the transparency of the proposed design. In order to obtain the balance between electrical performance and optical transmittivity (OT), we modify the metasurface structure to further improve the OT of the metantenna. The fabricated transparent metantenna shows an OT of more than 50%. A measured impedance bandwidth of 43.6% from 1.40 to 2.18 GHz is obtained to cover 2G and 3G wireless communication bands. Through designing the broadband rectifying circuit and the energy management circuit, we can obtain the maximum RF-dc efficiency of 65% and a stable dc output voltage of 3.4V, while the overall RF energy harvesting efficiency could reach 14.5% with the power input of 0 dBm. In addition, through the solar energy harvesting test, we can demonstrate the potential of the proposed design to work with solar panels for realizing efficient RF/solar hybrid energy harvesting.