Current Issue : April-June Volume : 2024 Issue Number : 2 Articles : 5 Articles
In recent years, due to the rise of the Internet of Things (IoT), various sensors have come to be in great demand for IoT devices. Analog-to-digital converters (ADCs) act as an important part of receivers in sensors. To improve the uptime of IoT devices, a bridged-switch energy-efficient switching scheme for successive approximation register (SAR) ADCs with a low-complexity capacitor drive circuit is proposed. The technique of top-plate sampling and closed-loop charge recycling is used in the proposed switching scheme so that neither the first nor the second comparison consumes switching energy. The third comparison uses bridge switches to connect the subarray to the main array, effectively reducing switching’s energy consumption. Only the least significant bit (LSB) is dependent on the accuracy of Vcm; thus, the last comparison consumes little switching energy. The proposed switching scheme achieves an average switching energy value of 47.5 CV2 ref, which is 96.52% lower than that of the conventional capacitor switching scheme and reduces the area by 75%. The other major circuit modules employed are bootstrapped switches, a fully dynamic comparator, and dynamic SAR logic. The proposed ADC was simulated under the conditions of 180 nm CMOS process and 1 MS/s, resulting in a 9.8-bit effective number of bits (ENOB), a signal-to-noise and distortion ratio (SNDR) of 60.76 dB, a spurious-free dynamic range (SFDR) of 69.85 dB, a power consumption of 14.7 μW, and a figure of merit (FoM) of 16.55 fJ/conv.-step....
Renewable energy sources play a pivotal role in the pursuit of sustainable and eco-friendly power solutions. While offering environmental benefits, they present inherent challenges. Photovoltaic systems rely on surrounding conditions, wind systems contend with variable wind speeds, and fuel cells are both costly and inefficient. Furthermore, the energy injected by renewable energy sources (RES) exhibits unpredictable behavior. To tackle these problems, researchers employ diverse power electronic devices and converters like inverters, power quality filters, and DC–DC choppers. Among these, DC–DC converters stand out for effectively regulating DC voltage and enhancing the efficiency of RESs. The meticulous selection of a suitable DC–DC converter, coupled with the integration of an efficient control technique, significantly influences overall power system performance. This paper introduces a novel approach to the design of switching controllers for DC–DC converters, specifically tailored for application in renewable energy systems. The proposed controller leverages the power of composite switched Lyapunov functions (CSLF) to enhance the efficiency and performance of DC–DC converters, addressing the unique challenges posed by renewable energy sources. Through comprehensive analysis and simulation, this study demonstrates the efficacy of the controller in optimizing power transfer, improving stability, and ensuring reliable operation in diverse renewable energy environments. Moreover, the small-scale DC–DC converter experiment’s findings are presented to confirm and validate the proposed scheme’s practical applicability....
A low-power delay-locked loop (DLL)-based frequency multiplier is presented. The multiplier is designed in 22 nm FDSOI and achieves 8× multiplication. The proposed DLL uses a new simple duty cycle correction circuit and is XOR logic-based for frequency multiplication. Current starved delay cells are used to make the circuit power efficient. The circuit uses three 2× stages instead of an edge combiner to achieve 8× multiplication, thus requiring far less power and chip area as compared to conventional phase-locked loop (PLL) circuits. The proposed 8× multiplier occupies an active area of 0.09 mm2. The measurement result shows ultra-low power consumption of 130 μW at 0.8 V supply. The post-layout simulation shows a timing jitter of 24 ps (pk-pk) at 2.44 GHz....
The high power density and long cyclic stability of N-doped carbon make it an attractive material for supercapacitor electrodes. Nevertheless, its low energy density limits its practical application. To solve the above issues, Fe2O3 embedded in N-doped porous carbon (Fe2O3/N-PC) was designed by pyrolyzing Hemin/activated carbon (Hemin/AC) composites. A porous structure allows rapid diffusion of electrons and ions during charge–discharge due to its large surface area and conductive channels. The redox reactions of Fe2O3 particles and N heteroatoms contribute to pseudocapacitance, which greatly enhances the supercapacitive performance. Fe2O3/N-PC showed a superior capacitance of 290.3 F g−1 at 1 A g−1 with 93.1% capacity retention after 10,000 charge–discharge cycles. Eventually, a high energy density of 37.6 Wh kg−1 at a power density of 1.6 kW kg−1 could be delivered with a solid symmetric device....
Two-dimensional materials are widely used as a new generation of functional materials for photovoltaic, photocatalyst, and nano-power devices. Strain engineering is a popular method to tune the properties of two-dimensional materials so that performances can be improved or more applications can be obtained. In this work, a two-dimensional heterostructure is constructed from SiC and GaN monolayers. Using first-principle calculations, the SiC/GaN heterostructure is stacked by a van der Waals interaction, acting as a semiconductor with an indirect bandgap of 3.331 eV. Importantly, the SiC/GaN heterostructure possesses a type-II band structure. Thus, the photogenerated electron and hole can be separated in the heterostructure as a potential photocatalyst for water splitting. Then, the external biaxial strain can decrease the bandgap of the SiC/GaN heterostructure. From pressure to tension, the SiC/GaN heterostructure realizes a transformation from a type-II to a type-I semiconductor. The strained SiC/GaN heterostructure also shows suitable band alignment to promote the redox of water splitting at pH 0 and 7. Moreover, the enhanced light-absorption properties further explain the SiC/GaN heterostructure’s potential as a photocatalyst and for nanoelectronics....
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