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J. Low Power Electron. Appl., Volume 13, Issue 2 (June 2023) – 19 articles

Cover Story (view full-size image): Scavenging ambient electromagnetic energy requires an antenna coupled to a rectifier, namely a rectenna. The hardware resources involved in fabricating a rectenna yield a significant carbon impact. Using an eco-friendlier substrate and a more economical fabrication process will help to lower the carbon impact. This article details the design and performance of a rectenna fabricated through plastronics, using poly(lactic) acid. Compared to an optimal substrate material, PLA exhibits a lower dielectric constant and higher losses but still remains adequate for a rectenna operation. A 2.45 GHz patch antenna demonstrates a gain very close to that of an antenna on an optimal substrate. A rectenna using a single series diode features an efficiency of 9.6% under -20 dBm input RF power and a load of 2 kW. View this paper
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16 pages, 885 KiB  
Article
Resonator Arrays for Linear Position Sensors
by Mattia Simonazzi, Leonardo Sandrolini and Andrea Mariscotti
J. Low Power Electron. Appl. 2023, 13(2), 41; https://doi.org/10.3390/jlpea13020041 - 07 Jun 2023
Viewed by 1401
Abstract
A contactless position sensor based on an array of magnetically coupled resonators and an external single coil cell is discussed for both stationary and dynamic applications. The simple structure allows the sensor to be adapted to the system in which it is installed [...] Read more.
A contactless position sensor based on an array of magnetically coupled resonators and an external single coil cell is discussed for both stationary and dynamic applications. The simple structure allows the sensor to be adapted to the system in which it is installed and can be used to detect the positions of objects in motion that bear an external resonator coil that does not necessitate a supply. By exploiting the unique behaviour of the array input impedance, it is possible to identify the position of the external resonator by exciting the first array cell with an external voltage source and measuring the resulting input current. The system is robust and suitable for application in harsh environments. The sensitivity of the measured input impedance to the space variation is adjustable with the definition of the array geometry and is analysed. Different configurations of the array and external resonator are considered, and the effects of various termination conditions and the resulting factor of merit after changing the coil resistance are discussed. The proposed procedure is numerically validated for an array of ten identical magnetically coupled resonators with 15 cm side lengths. Simulations carried out for a distance of up to 20 cm show that, with a quality factor lower than 100 and optimal terminations of both the array and external coil, it is possible to detect the position of the latter. Full article
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16 pages, 2456 KiB  
Article
Efficient GEMM Implementation for Vision-Based Object Detection in Autonomous Driving Applications
by Fatima Zahra Guerrouj, Sergio Rodríguez Flórez, Mohamed Abouzahir, Abdelhafid El Ouardi and Mustapha Ramzi
J. Low Power Electron. Appl. 2023, 13(2), 40; https://doi.org/10.3390/jlpea13020040 - 06 Jun 2023
Cited by 1 | Viewed by 1685
Abstract
Convolutional Neural Networks (CNNs) have been incredibly effective for object detection tasks. YOLOv4 is a state-of-the-art object detection algorithm designed for embedded systems. It is based on YOLOv3 and has improved accuracy, speed, and robustness. However, deploying CNNs on embedded systems such as [...] Read more.
Convolutional Neural Networks (CNNs) have been incredibly effective for object detection tasks. YOLOv4 is a state-of-the-art object detection algorithm designed for embedded systems. It is based on YOLOv3 and has improved accuracy, speed, and robustness. However, deploying CNNs on embedded systems such as Field Programmable Gate Arrays (FPGAs) is difficult due to their limited resources. To address this issue, FPGA-based CNN architectures have been developed to improve the resource utilization of CNNs, resulting in improved accuracy and speed. This paper examines the use of General Matrix Multiplication Operations (GEMM) to accelerate the execution of YOLOv4 on embedded systems. It reviews the most recent GEMM implementations and evaluates their accuracy and robustness. It also discusses the challenges of deploying YOLOv4 on autonomous vehicle datasets. Finally, the paper presents a case study demonstrating the successful implementation of YOLOv4 on an Intel Arria 10 embedded system using GEMM. Full article
(This article belongs to the Special Issue Advances in Embedded Artificial Intelligence and Internet-of-Things)
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26 pages, 18945 KiB  
Article
Nanomaterial-Based Sensor Array Signal Processing and Tuberculosis Classification Using Machine Learning
by Chenxi Liu, Israel Cohen, Rotem Vishinkin and Hossam Haick
J. Low Power Electron. Appl. 2023, 13(2), 39; https://doi.org/10.3390/jlpea13020039 - 29 May 2023
Viewed by 1818
Abstract
Tuberculosis (TB) has long been recognized as a significant health concern worldwide. Recent advancements in noninvasive wearable devices and machine learning (ML) techniques have enabled rapid and cost-effective testing for the real-time detection of TB. However, small datasets are often encountered in biomedical [...] Read more.
Tuberculosis (TB) has long been recognized as a significant health concern worldwide. Recent advancements in noninvasive wearable devices and machine learning (ML) techniques have enabled rapid and cost-effective testing for the real-time detection of TB. However, small datasets are often encountered in biomedical and chemical engineering domains, which can hinder the success of ML models and result in overfitting issues. To address this challenge, we propose various data preprocessing methods and ML approaches, including long short-term memory (LSTM), convolutional neural network (CNN), Gramian angular field-CNN (GAF-CNN), and multivariate time series with MinCutPool (MT-MinCutPool), for classifying a small TB dataset consisting of multivariate time series (MTS) sensor signals. Our proposed methods are compared with state-of-the-art models commonly used in MTS classification (MTSC) tasks. We find that lightweight models are more appropriate for small-dataset problems. Our experimental results demonstrate that the average performance of our proposed models outperformed the baseline methods in all aspects. Specifically, the GAF-CNN model achieved the highest accuracy of 0.639 and the highest specificity of 0.777, indicating its superior effectiveness for MTSC tasks. Furthermore, our proposed MT-MinCutPool model surpassed the baseline MTPool model in all evaluation metrics, demonstrating its viability for MTSC tasks. Full article
(This article belongs to the Special Issue Advances in Embedded Artificial Intelligence and Internet-of-Things)
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2 pages, 194 KiB  
Editorial
Ultra-Low-Power ICs for the Internet of Things
by Orazio Aiello
J. Low Power Electron. Appl. 2023, 13(2), 38; https://doi.org/10.3390/jlpea13020038 - 26 May 2023
Cited by 1 | Viewed by 1353
Abstract
The collection of research works in this Special Issue focuses on Ultra-Low-Power (ULP) Integrated Circuits (ICs) operating under a tight budget of power as a criterion to build electronic devices relying less and less on batteries [...] Full article
(This article belongs to the Special Issue Ultra-Low-Power ICs for the Internet of Things)
12 pages, 5396 KiB  
Article
Ultra-Low Power Programmable Bandwidth Capacitively-Coupled Chopper Instrumentation Amplifier Using 0.2 V Supply for Biomedical Applications
by Xuan Thanh Pham, Xuan Thuc Kieu and Manh Kha Hoang
J. Low Power Electron. Appl. 2023, 13(2), 37; https://doi.org/10.3390/jlpea13020037 - 24 May 2023
Viewed by 1616
Abstract
This paper presents a capacitively coupled chopper instrumentation amplifier (CCIA) with ultra-low power consumption and programmable bandwidth for biomedical applications. To achieve a flexible bandwidth from 0.2 to 10 kHz without additional power consumption, a programmable Miller compensation technique was proposed and used [...] Read more.
This paper presents a capacitively coupled chopper instrumentation amplifier (CCIA) with ultra-low power consumption and programmable bandwidth for biomedical applications. To achieve a flexible bandwidth from 0.2 to 10 kHz without additional power consumption, a programmable Miller compensation technique was proposed and used in the CCIA. By using a Squeezed inverter amplifier (SQI) that employs a 0.2-V supply, the proposed CCIA addresses the primary noise source in the first stage, resulting in high noise power efficiency. The proposed CCIA is designed using a 0.18 µm CMOS technology process and has a chip area of 0.083 mm2. With a power consumption of 0.47 µW at 0.2 and 0.8 V supply, the proposed amplifier architecture achieves a thermal noise of 28 nV/√Hz, an input-related noise (IRN) of 0.9 µVrms, a closed-loop gain (AV) of 40 dB, a power supply rejection ratio (PSRR) of 87.6 dB, and a common-mode rejection ratio (CMRR) of 117.7 dB according to post-simulation data. The proposed CCIA achieves a noise efficiency factor (NEF) of 1.47 and a power efficiency factor (PEF) of 0.56, which allows comparison with the latest research results. Full article
(This article belongs to the Special Issue Ultra-Low-Power ICs for the Internet of Things Vol. 2)
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13 pages, 1924 KiB  
Article
AMA: An Ageing Task Migration Aware for High-Performance Computing
by Emmanuel Ofori-Attah and Michael Opoku Agyeman
J. Low Power Electron. Appl. 2023, 13(2), 36; https://doi.org/10.3390/jlpea13020036 - 22 May 2023
Cited by 1 | Viewed by 1203
Abstract
The dark-silicon challenge poses a design problem for future many-core systems. As a result of this, several techniques have been introduced to improve the number of processing elements that can be powered on. One of the techniques employed by many is Task Migration. [...] Read more.
The dark-silicon challenge poses a design problem for future many-core systems. As a result of this, several techniques have been introduced to improve the number of processing elements that can be powered on. One of the techniques employed by many is Task Migration. In this paper, an Ageing Task Migration Aware for High-Performance Computing (AMA) is proposed to improve the lifetime of nodes. The proposed method determines which clusters applications are mapped to and migrates high-demand tasks amongst nodes to improve the lifetime at every epoch. Experimental results show that the proposed method outperforms state-of-the-art techniques by more than 10%. Full article
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19 pages, 20132 KiB  
Article
Evaluation of Polylactic Acid Polymer as a Substrate in Rectenna for Ambient Radiofrequency Energy Harvesting
by Pangsui Usifu Linge, Tony Gerges, Pascal Bevilacqua, Jean-Marc Duchamp, Philippe Benech, Jacques Verdier, Philippe Lombard, Michel Cabrera, Pierre Tsafack, Fabien Mieyeville and Bruno Allard
J. Low Power Electron. Appl. 2023, 13(2), 34; https://doi.org/10.3390/jlpea13020034 - 12 May 2023
Viewed by 1844
Abstract
This work details the design and experimental characterization of a 2D rectenna for scavenging radio frequency energy at 2.45 GHz (WiFi band), fabricated on polylactic acid polymer (PLA) using a plastronics approach. PLA is the RF substrate of both antenna and rectifier. The [...] Read more.
This work details the design and experimental characterization of a 2D rectenna for scavenging radio frequency energy at 2.45 GHz (WiFi band), fabricated on polylactic acid polymer (PLA) using a plastronics approach. PLA is the RF substrate of both antenna and rectifier. The two transmission line (TTL) approach is used to characterize the substrate properties to be considered during design. A linearly polarized patch antenna with microstrip transmission feeding is connected to a single series diode rectifier through a T-matching network. The antenna has simulated and measured gain of 7.6 dB and 7.5 dB, respectively. The rectifier has a measured DC output power of 0.96 μW at an optimal load of 2 kΩ under RF input power of −20 dBm at 2.45 GHz. The power conversion efficiency is 9.6% in the latter conditions for a 54 × 36 mm patch antenna of a 1.5 mm thick PLA substrate obtained from additive manufacturing. The power conversion efficiency reaches a value of 28.75% when the input power is −10 dBm at 2.45 GHz. This corresponds to a peak DC power of 28.75 μW when the optimal load is 1.5 kΩ. The results compare significantly with the ones of a similar rectenna circuit manufactured on preferred RF substrate. Full article
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20 pages, 2293 KiB  
Article
A 0.15-to-0.5 V Body-Driven Dynamic Comparator with Rail-to-Rail ICMR
by Riccardo Della Sala, Valerio Spinogatti, Cristian Bocciarelli, Francesco Centurelli and Alessandro Trifiletti
J. Low Power Electron. Appl. 2023, 13(2), 35; https://doi.org/10.3390/jlpea13020035 - 11 May 2023
Cited by 3 | Viewed by 1770
Abstract
In this paper, a novel dynamic body-driven ultra-low voltage (ULV) comparator is presented. The proposed topology takes advantage of the back-gate configuration by driving the input transistors’ gates with a clocked positive feedback loop made of two AND gates. This allows for the [...] Read more.
In this paper, a novel dynamic body-driven ultra-low voltage (ULV) comparator is presented. The proposed topology takes advantage of the back-gate configuration by driving the input transistors’ gates with a clocked positive feedback loop made of two AND gates. This allows for the removal of the clocked tail generator, which decreases the number of stacked transistors and improves performance at low VDD. Furthermore, the clocked feedback loop causes the comparator to behave as a full CMOS latch during the regeneration phase, which means no static power consumption occurs after the outputs have settled. Thanks to body driving, the proposed comparator also achieves rail-to-rail input common mode range (ICMR), which is a critical feature for circuits that operate at low and ultra-low voltage headrooms. The comparator was designed and optimized in a 130-nm technology from STMicroelectronics at VDD=0.3 V and is able to operate at up to 2 MHz with an input differential voltage of 1 mV. The simulations show that the comparator remains fully operational even when the supply voltage is scaled down to 0.15 V, in which case the circuit exhibits a maximum operating frequency of 80 kHz at Vid=1 mV. Full article
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21 pages, 1700 KiB  
Article
In-Pipeline Processor Protection against Soft Errors
by Ján Mach, Lukáš Kohútka and Pavel Čičák
J. Low Power Electron. Appl. 2023, 13(2), 33; https://doi.org/10.3390/jlpea13020033 - 10 May 2023
Cited by 1 | Viewed by 2436
Abstract
The shrinking of technology nodes allows higher performance, but susceptibility to soft errors increases. The protection has been implemented mainly by lockstep or hardened process techniques, which results in a lower frequency, a larger area, and higher power consumption. We propose a protection [...] Read more.
The shrinking of technology nodes allows higher performance, but susceptibility to soft errors increases. The protection has been implemented mainly by lockstep or hardened process techniques, which results in a lower frequency, a larger area, and higher power consumption. We propose a protection technique that only slightly affects the maximal frequency. The area and power consumption increase are comparable with dual lockstep architectures. A reaction to faults and the ability to recover from them is similar to triple modular redundancy architectures. The novelty lies in applying redundancy into the processor’s pipeline and its separation into two sections. The protection provides fast detection of faults, simple recovery by a flush of the pipeline, and allows a large prediction unit to be unprotected. A proactive component automatically scrubs a register file to prevent fault accumulation. The whole protection scheme can be fully implemented at the register transfer level. We present the protection scheme implemented inside the RISC-V core with the RV32IMC instruction set. Simulations confirm that the protection can handle the injected faults. Synthesis shows that the protection lowers the maximum frequency by only about 3.9%. The area increased by 108% and power consumption by 119%. Full article
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13 pages, 1777 KiB  
Article
A Time-Mode PWM 1st Order Low-Pass Filter
by Konstantinos P. Pagkalos, Orfeas Panetas-Felouris and Spyridon Vlassis
J. Low Power Electron. Appl. 2023, 13(2), 32; https://doi.org/10.3390/jlpea13020032 - 06 May 2023
Viewed by 2150
Abstract
In this work, a first-order low-pass filter is proposed as suitable for time-mode PWM signal processing. In time-mode PWM signal processing, the pulse width of a rectangular pulse is the processing variable. The filter is constructed using basic time-mode building blocks such as [...] Read more.
In this work, a first-order low-pass filter is proposed as suitable for time-mode PWM signal processing. In time-mode PWM signal processing, the pulse width of a rectangular pulse is the processing variable. The filter is constructed using basic time-mode building blocks such as time registers and time adders and so it is characterized by low complexity which can lead to the modular and versatile design of higher-order filters. All the building blocks of the filter were designed and verified in a TSMC 65 nm technology process. The sampling frequency was 5 MHz, the gain of the filter at low frequencies was at −0.016 dB, the cut-off frequency was 1.2323 MHz, and the power consumption was around 59.1 μW. Full article
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23 pages, 27127 KiB  
Article
Batteryless Sensor Devices for Underground Infrastructure—A Long-Term Experiment on Urban Water Pipes
by Manuel Boebel, Fabian Frei, Frank Blumensaat, Christian Ebi, Marcel Louis Meli and Andreas Rüst
J. Low Power Electron. Appl. 2023, 13(2), 31; https://doi.org/10.3390/jlpea13020031 - 29 Apr 2023
Cited by 2 | Viewed by 2067
Abstract
Drinking water is becoming increasingly scarce as the world’s population grows and climate change continues. However, there is great potential to improve drinking water pipelines, as 30% of fresh water is lost between the supplier and consumer. While systematic process monitoring could play [...] Read more.
Drinking water is becoming increasingly scarce as the world’s population grows and climate change continues. However, there is great potential to improve drinking water pipelines, as 30% of fresh water is lost between the supplier and consumer. While systematic process monitoring could play a crucial role in the early detection and repair of leaks, current practice requires manual inspection, which is both time-consuming and costly. This project envisages maintenance-free measurements at numerous locations within the underground infrastructure, a goal that is to be achieved through the use of a harvesting device mounted on the water pipe. This device extracts energy from the temperature difference between the water pipe and the soil using a TEG (thermoelectric generator), takes sensor measurements, processes the data and transmits it wirelessly via LoRaWAN. We built 16 harvesting devices, installed them in four locations and continuously evaluated their performance throughout the project. In this paper, we focus on two devices of a particular type. The data for a full year show that enough energy was available on 94% of the days, on average, to take measurements and transmit data. This study demonstrates that it is possible to power highly constrained sensing devices with energy harvesting in underground environments. Full article
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21 pages, 1537 KiB  
Article
Energy-Efficient Audio Processing at the Edge for Biologging Applications
by Jonathan Miquel, Laurent Latorre and Simon Chamaillé-Jammes
J. Low Power Electron. Appl. 2023, 13(2), 30; https://doi.org/10.3390/jlpea13020030 - 27 Apr 2023
Cited by 1 | Viewed by 1659
Abstract
Biologging refers to the use of animal-borne recording devices to study wildlife behavior. In the case of audio recording, such devices generate large amounts of data over several months, and thus require some level of processing automation for the raw data collected. Academics [...] Read more.
Biologging refers to the use of animal-borne recording devices to study wildlife behavior. In the case of audio recording, such devices generate large amounts of data over several months, and thus require some level of processing automation for the raw data collected. Academics have widely adopted offline deep-learning-classification algorithms to extract meaningful information from large datasets, mainly using time-frequency signal representations such as spectrograms. Because of the high deployment costs of animal-borne devices, the autonomy/weight ratio remains by far the fundamental concern. Basically, power consumption is addressed using onboard mass storage (no wireless transmission), yet the energy cost associated with data storage activity is far from negligible. In this paper, we evaluate various strategies to reduce the amount of stored data, making the fair assumption that audio will be categorized using a deep-learning classifier at some point of the process. This assumption opens up several scenarios, from straightforward raw audio storage paired with further offline classification on one side, to a fully embedded AI engine on the other side, with embedded audio compression or feature extraction in between. This paper investigates three approaches focusing on data-dimension reduction: (i) traditional inline audio compression, namely ADPCM and MP3, (ii) full deep-learning classification at the edge, and (iii) embedded pre-processing that only computes and stores spectrograms for later offline classification. We characterized each approach in terms of total (sensor + CPU + mass-storage) edge power consumption (i.e., recorder autonomy) and classification accuracy. Our results demonstrate that ADPCM encoding brings 17.6% energy savings compared to the baseline system (i.e., uncompressed raw audio samples). Using such compressed data, a state-of-the-art spectrogram-based classification model still achieves 91.25% accuracy on open speech datasets. Performing inline data-preparation can significantly reduce the amount of stored data allowing for a 19.8% energy saving compared to the baseline system, while still achieving 89% accuracy during classification. These results show that while massive data reduction can be achieved through the use of inline computation of spectrograms, it translates to little benefit on device autonomy when compared to ADPCM encoding, with the added downside of losing original audio information. Full article
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23 pages, 2675 KiB  
Article
Battery Parameter Analysis through Electrochemical Impedance Spectroscopy at Different State of Charge Levels
by Yuchao Wu, Sneha Sundaresan and Balakumar Balasingam
J. Low Power Electron. Appl. 2023, 13(2), 29; https://doi.org/10.3390/jlpea13020029 - 26 Apr 2023
Viewed by 3085
Abstract
This paper presents a systematic approach to extract electrical equivalent circuit model (ECM) parameters of the Li-ion battery (LIB) based on electrochemical impedance spectroscopy (EIS). Particularly, the proposed approach is suitable to practical applications where the measurement noise can be significant, resulting in [...] Read more.
This paper presents a systematic approach to extract electrical equivalent circuit model (ECM) parameters of the Li-ion battery (LIB) based on electrochemical impedance spectroscopy (EIS). Particularly, the proposed approach is suitable to practical applications where the measurement noise can be significant, resulting in a low signal-to-noise ratio. Given the EIS measurements, the proposed approach can be used to obtain the ECM parameters of a battery. Then, a time domain approach is employed to validate the accuracy of estimated ECM parameters. In order to investigate whether the ECM parameters vary as the battery’s state of charge (SOC) changes, the EIS experiment was repeated at nine different SOCs. The experimental results show that the proposed approach is consistent in estimating the ECM parameters. It is found that the battery parameters, such as internal resistance, capacitance and inductance, remain the same for practical SOC ranges starting from 20% until 90%. The ECM parameters saw a significant change at low SOC levels. Furthermore, the experimental data show that the resistive components estimated in the frequency domain are very close to the internal resistance estimated in the time domain. The proposed approach was applied to eight different battery cells consisting of two different manufacturers and produced consistent results. Full article
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17 pages, 9563 KiB  
Article
Class AB Voltage Follower and Low-Voltage Current Mirror with Very High Figures of Merit Based on the Flipped Voltage Follower
by Jaime Ramírez-Angulo, Anindita Paul, Manaswini Gangineni, Jose Maria Hinojo-Montero and Jesús Huerta-Chua
J. Low Power Electron. Appl. 2023, 13(2), 28; https://doi.org/10.3390/jlpea13020028 - 24 Apr 2023
Viewed by 2974
Abstract
The application of the flipped voltage follower to implement two high-performance circuits is presented: (1) The first is a class AB cascode flipped voltage follower that shows an improved slew rate and an improved bandwidth by very large factors and that has a [...] Read more.
The application of the flipped voltage follower to implement two high-performance circuits is presented: (1) The first is a class AB cascode flipped voltage follower that shows an improved slew rate and an improved bandwidth by very large factors and that has a higher output range than the conventional flipped voltage follower. It has a small signal figure of merit FOMSS = 46 MHz pF/µW and a current efficiency figure of merit FOMCE = 118. This is achieved by just introducing an additional output current sourcing PMOS transistor (P-channel Metal Oxide Semiconductor Field Effect Transistor) that provides dynamic output current enhancement and increases the quiescent power dissipation by less than 10%. (2) The other is a high-performance low-voltage current mirror with a nominal gain accuracy better than 0.01%, 0.212 Ω input resistance, 112 GΩ output resistance, 1 V supply voltage requirements, 0.15 V input, and 0.2 V output compliance voltages. These characteristics are achieved by utilizing two auxiliary amplifiers and a level shifter that increase the power dissipation just moderately. Post-layout simulations verify the performance of the circuits in a commercial 180 nm CMOS (Complementary Metal Oxide Semiconductor) technology. Full article
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18 pages, 8732 KiB  
Article
Buck-Boost Charge Pump Based DC-DC Converter
by Evi Keramida, George Souliotis, Spyridon Vlassis and Fotis Plessas
J. Low Power Electron. Appl. 2023, 13(2), 27; https://doi.org/10.3390/jlpea13020027 - 21 Apr 2023
Cited by 1 | Viewed by 3037
Abstract
This paper presents a novel inductorless dual-mode buck-boost charge pump (CP) based DC-DC converter. The proposed architecture allows the same circuit to accomplish two modes of operation, buck and boost, for degrading or elevating the output voltage, respectively, compared to the input. To [...] Read more.
This paper presents a novel inductorless dual-mode buck-boost charge pump (CP) based DC-DC converter. The proposed architecture allows the same circuit to accomplish two modes of operation, buck and boost, for degrading or elevating the output voltage, respectively, compared to the input. To achieve each mode, only a switching of the input–output connections is needed without any other modification in the design of the DC-DC converter. The dual-mode configuration aims to merge two different functions into one circuit, minimizing the design time and the area the DC-DC converter occupies on the die. The proposed buck-boost CP has been designed using TSMC 65 nm complementary metal–oxide–semiconductor (CMOS) technology. The functional input voltage range of the CP in boost mode is 1.2 V to 1.8 V and the typical output voltage is 1.8 V. For the buck mode, the input voltage range is 3.2 V to 3.6 V and the output is 1.5 V. For both modes, the output can be easily modified to new values by changing the comparator configuration. Efficiency results are also provided for the two modes. Full article
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16 pages, 3678 KiB  
Article
Innovative Characterization and Comparative Analysis of Water Level Sensors for Enhanced Early Detection and Warning of Floods
by Rula Tawalbeh, Feras Alasali, Zahra Ghanem, Mohammad Alghazzawi, Ahmad Abu-Raideh and William Holderbaum
J. Low Power Electron. Appl. 2023, 13(2), 26; https://doi.org/10.3390/jlpea13020026 - 11 Apr 2023
Cited by 2 | Viewed by 2485
Abstract
In considering projections that flooding will increase in the future years due to factors such as climate change and urbanization, the need for dependable and accurate water sensors systems is greater than ever. In this study, the performance of four different water level [...] Read more.
In considering projections that flooding will increase in the future years due to factors such as climate change and urbanization, the need for dependable and accurate water sensors systems is greater than ever. In this study, the performance of four different water level sensors, including ultrasonic, infrared (IR), and pressure sensors, is analyzed based on innovative characterization and comparative analysis, to determine whether or not these sensors have the ability to detect rising water levels and flash floods at an earlier stage under different conditions. During our exhaustive tests, we subjected the device to a variety of conditions, including clean and contaminated water, light and darkness, and an analogue connection to a display. When it came to monitoring water levels, the ultrasonic sensors stood out because of their remarkable precision and consistency. To address this issue, this study provides a novel and comparative examination of four water level sensors to determine which is the most effective and cost-effective in detecting floods and water level fluctuations. The IR sensor delivered accurate findings; however, it demonstrated some degree of variability throughout the course of the experiment. In addition, the results of our research show that the pressure sensor is a legitimate alternative to ultrasonic sensors. This presents a possibility that is more advantageous financially when it comes to the development of effective water level monitoring systems. The findings of this study are extremely helpful in improving the dependability and accuracy of flood detection systems and, eventually, in lessening the devastation caused by natural catastrophes. Full article
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13 pages, 2777 KiB  
Communication
First Review of Conductive Electrets for Low-Power Electronics
by D. D. L. Chung
J. Low Power Electron. Appl. 2023, 13(2), 25; https://doi.org/10.3390/jlpea13020025 - 06 Apr 2023
Cited by 1 | Viewed by 1810
Abstract
This is the first review of conductive electrets (unpoled carbons and metals), which provide a new avenue for low-power electronics. The electret provides low DC voltage (μV) while allowing low DC current (μA) to pass through. Ohm’s Law is obeyed. The voltage scales [...] Read more.
This is the first review of conductive electrets (unpoled carbons and metals), which provide a new avenue for low-power electronics. The electret provides low DC voltage (μV) while allowing low DC current (μA) to pass through. Ohm’s Law is obeyed. The voltage scales with the inter-electrode distance. Series connection of multiple electret components provides a series voltage that equals the sum of the voltages of the components if there is no bending at the connection between the components. Otherwise, the series voltage is below the sum. Bending within the component also diminishes the voltage because of the polarization continuity decrease. The electret originates from the interaction of a tiny fraction of the carriers with the atoms. This interaction results in the charge in the electret. Dividing the electret charge by the electret voltage V’ provides the electret-based capacitance C’, which is higher than the permittivity-based capacitance (conventional) by a large number of orders of magnitude. The C’ governs the electret energy (1/2 CV2) and electret discharge time constant (RC’, where R = resistance), as shown for metals. The discharge time is promoted by a larger inter-electrode distance. The electret discharges occur upon short-circuiting and charge back upon subsequent opencircuiting. The discharge or charge of the electret amounts to the discharge or charge of C’. Full article
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11 pages, 7880 KiB  
Communication
A 0.6 V Bulk-Driven Class-AB Two-Stage OTA with Non-Tailed Differential Pair
by Andrea Ballo, Alfio Dario Grasso and Salvatore Pennisi
J. Low Power Electron. Appl. 2023, 13(2), 24; https://doi.org/10.3390/jlpea13020024 - 28 Mar 2023
Cited by 2 | Viewed by 1823
Abstract
This work presents a two-stage operational transconductance amplifier suitable for sub-1 V operation. This characteristic is achieved thanks to the adoption of a bulk-driven non-tailed differential pair. Local positive feedback is exploited to boost the equivalent transconductance of the first stage and the [...] Read more.
This work presents a two-stage operational transconductance amplifier suitable for sub-1 V operation. This characteristic is achieved thanks to the adoption of a bulk-driven non-tailed differential pair. Local positive feedback is exploited to boost the equivalent transconductance of the first stage and the quasi-floating gate approach enables the class AB operation of the second stage. Implemented in a standard 180 nm CMOS technology and supplied at 0.6 V, the amplifier exhibits a 350 kHz gain bandwidth product and a phase margin of 69° while driving a 150 pF load. Compared to other solutions in the literature, the proposed one exhibits a considerable performance improvement, especially for large signal operation. Full article
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19 pages, 10651 KiB  
Article
A Ka-Band SiGe BiCMOS Quasi-F−1 Power Amplifier Using a Parasitic Capacitance Cancellation Technique
by Vasileios Manouras and Ioannis Papananos
J. Low Power Electron. Appl. 2023, 13(2), 23; https://doi.org/10.3390/jlpea13020023 - 24 Mar 2023
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Abstract
This paper deals with the design, analysis, and implementation of a Ka-band, single-stage, quasi-inverse class F power amplifier (PA). A detailed methodology for the evaluation of the active device’s output capacitance is described, enabling the designing of a second-harmonically tuned load and resulting [...] Read more.
This paper deals with the design, analysis, and implementation of a Ka-band, single-stage, quasi-inverse class F power amplifier (PA). A detailed methodology for the evaluation of the active device’s output capacitance is described, enabling the designing of a second-harmonically tuned load and resulting in enhanced performance. A simplified model for the extraction of time-domain intrinsic voltage and current waveforms at the output of the main active core is introduced, enforcing the implementation process of the proposed quasi-inverse class F technique. The PA is fabricated in a 130 nm SiGe BiCMOS technology with fT/fmax=250/370 GHz and it is suitable for 5G applications. It achieves 33% peak power-added efficiency (PAE), 18.8 dBm saturation output power Psat, and 14.7 dB maximum large-signal power gain G at the operating frequency of 38 GHz. The PA’s response is also tested under a modulated-signal excitation and simulation results are denoted in this paper. The chip size is 0.605×0.712 mm2 including all pads. Full article
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