1,720,992 research outputs found
RF Energy Harvester Rectifier Block Design Optimization: A Comparison with a Commercial Device
No full textIn this work, we first analyse and measure a commercial RF energy harvesting device from Powercast, a very good device useful for several applications, after we propose a rectifier design that can be utilized in order to improve the conversion efficiency in low voltage energy harvested systems. Stating from a dual-stage Dickinson voltage rectifier we have designed a proper matching network and implemented a prototype board measured with success. The tests were done for both the frequencies of 900 MHz and 915 MHz and results proved the better performance of the custom-designed harvester for all the measuring conditions, with an efficiency peak of up to 75%
A low-noise figure and quasi-constant Q in DCS band tunable active filter
No full textThis work focuses on the implementation of a tunable active filter with an almost constant quality factor. Especially for monolithic microwave integrated circuits, active filters are typically implemented by realizing active inductors, which compensates losses typical of real ones; however, these just show good inductance in a narrow band, usually reducing Q for changes of frequency and making tunability harder. The proposed circuit involves an active capacitance approach, using active component to compensate for inductors losses and making the system voltage-tunable using a varactor, keeping the Q almost unvaried. Also, good noise performances are obtained compared to other common active filter approaches
Micro Energy Harvesting from the Soil of Indoor Living Plants
No full textIn this work, the aim is to propose a study on living plants characterization as an energy source for electricity scavenging to feed low-power devices and autonomous sensors. Nowadays, the widespread of the Internet of Things (loT) and distributed monitoring has led to an increasing demand for autonomous, long-life low-power smart devices. As a consequence, research on alternative energy sources in the surrounding environment, with zero costs and reduced bio impact, is growing. This work demonstrates the feasibility of a plant-based energy harvesting system capable of constantly extracting energy in the order of hundreds of microwatts. The achieved results enable future research works on practical electronic systems to include the energy extraction process from living plants to supply embedded systems for plant monitoring or other similar applications
A Second Order 1.8–1.9 GHz Tunable Active Band-Pass Filter with Improved Noise Performances
No full textIn this paper, a novel active tunable band-pass filter with improved noise performances is presented. This filter is based on a negative resistance circuit (or active capacitance), where the gain obtained with a transistor is used to compensate for inductor losses. Moreover, the capacitance of the resonator is obtained through a voltage-controlled reverse-biased varactor, which allows for frequency tuning. Despite the active component, the proposed filter also has good noise performance. Measurements show a tunability range from 1.816 GHz to 1.886 GHz, with a bandwidth of 38 MHz. The insertion loss maximum value is 0.4 dB, while the noise figure value has a minimum value of 2.5 dB at the center frequency within the tunability range
Control Circuits for Adjustable Digitally Programmed DC Power Supplies
No full textThis paper presents and compare two methods for digital output programming and regulation of Switched Mode Power Supplies. One method is based on shunt regulator TL431 emulation, while the other uses injected current into the reference resistor divider. Both methods are tested on LM3481-EVM commercial module and have shown good linearity and satisfactory control performances on output voltage regulation. Finally, control accuracy of the two methods is discussed
IoT Battery-Less System for Plant Health Monitoring
No full textIn this work, we introduce an innovative battery-less Internet of Things (IoT) device designed specifically for the purpose of monitoring plant health. This system operates by gathering energy directly from the soil where the plant is rooted, employing a combination of the electrode potential principle and a cutting-edge maximum power point tracking algorithm, optimizing energy harvesting and ensuring that the system operates at peak efficiency. The harvested energy is efficiently stored within a supercapacitor, which subsequently serves as the primary power source for a highly energy-efficient System on a Chip (SoC). This SoC, in turn, is responsible for collecting and transmitting data related to light conditions and soil humidity. The data is transmitted via Bluetooth Low-Energy (BLE) technology, making it accessible for remote monitoring and analysis. Initial results from our research showcase the remarkable feasibility of the proposed system. We have successfully demonstrated its capability to extract energy from the environment, as evidenced by a fully functional prototype that relies solely on energy harvested through this method. A 330 μF capacitor has been charged in less than 3 min for the initial power-on of the whole system and less than 20 s after the initial startup, providing a 3 mA current to a standard LED for about 300 ms
Current-Mode Transimpedance Sample-and-Hold using clocked Voltage Conveyor
No full textIn this paper, a current-mode Sample and Hold circuit with voltage output and a reduced input impedance is presented. The proposed circuit is based on a Second-Generation Voltage Conveyor (VCII) in a standard 0.18 μm CMOS technology. Some sensors, such as photodiodes, provide current signals that require a suitable interface to be properly detected. In addition, for autonomous multi-sensorial devices, reduced power consumption and small voltages are typically needed. The transimpedance behavior of the voltage conveyor make it suitable for interfacing with modern Analog-to-Digital conversion. Current and voltage buffering of the VCII can provide a good precision and dynamic range while maintaining reduced consumptions. In addition to this, a low output impedance is obtained to enhance driving capability. The proposed solution has been simulated using a standard 0.18 μm CMOS technology, and operates at ± 0.75V power supply, achieving an input impedance of 68 Ω with an input dynamic range of ± 10μ A and a static power consumption of 74 μ W. The use of a small 0.3 pF capacitor allowed the system to achieve a settling time smaller than 50 ns settling with an accuracy error is approximately equal to 1%, allowing a sampling rate of 20 MHz
Low-Power VCII-Based Current-Mode Schmitt Trigger with High Drive Capabilities
No full textIn this paper, a novel CMOS current-mode Schmitt Trigger based on the Second Generation Voltage Conveyor (VCII) is proposed. The circuit has been designed in a standard CMOS 150 nm technology with a dual ±1.65 V voltage supply, and simulations and layout were carried out on Cadence Virtuoso. Low power consumption is obtained using a class AB current input stage and a class B voltage push-pull output stage, providing two voltage outputs to better suit the load of the trigger. Static and transient simulations, as well as PVT and Montecarlo analyses, were performed. The designed VCII shows an output saturation value of approximately ±1.18 V on the high-drive output, used to generate the threshold, a mismatch of about 10mV between positive and negative values, and a rail-to-rail output. The static power consumption is 37 μW, and the high-drive capability overcomes ±98 V /μs and 100 ns propagation delay, making the proposed circuit suitable to be used as a Schmitt Trigger
Energy harvesting techniques for sensory glove systems
No full textWe proposed and addressed methods for using multiple energy harvesting strategies to power a wearable sensory glove. The capabilities of piezoelectric and thermal energy harvesters were reported, with hand motions and body heat used to these goals. A potential multi-input single-output DC-DC architecture was proposed to harvest energy from the two sources, and power analysis results were used to assess the harvesting system viability in terms of the amount of gathered power required to power the target applications
Realization of an Electronically Tunable Resistor-Less Floating Inductance Simulator Using VCII
No full textIn this paper, a new implementation of an electronically tunable resistor-less floating inductance simulator using a second-generation voltage conveyor (VCII) is presented. The proposed circuit is resistor-free (benefiting from the intrinsic resistors at the Y terminals of the employed VCIIs) and composed of three VCIIs and a single grounded capacitor. Using a control current (Icon), the value of impedance at the Y terminal of the VCII is varied, whereby the value of the simulated inductance is tuned. The proposed circuit is designed at a transistor level using 0.18 µm TSMC CMOS parameters and ±0.9 V supply voltage. PSpice simulations are carried out to confirm the effectiveness of the proposed circuit. For a range of Icon from 0 µA to 50 µA, the value of the simulated L can be varied from −576 µH to −324 µH and from +316 µH to +576 µH for negative and positive simulators, respectively, in the frequency range of 100 kHz–3 MHz. Favorably, the value of the series resistance remains below 76 Ω. Simulation results show an error value below 4.8% and power consumption variation is from 1.64 mW to 1.92 mW. Moreover, application of the proposed circuit as a standard band-pass RLC filter is also included
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