Amplifier Circuit Research Articles

Infrared Trace Gas Sensing With a Fast Perovskite Nano-Structure Laser Photodetector

In the present work, we firstly demonstrated infrared perovskite nanorods as a state-of-the-art fast photo-sensing core so that they could adapt to the demand of infrared trace gas sensing. Periodic perovskite nanorods can enhance light absorption in the infrared regime, boost the distributed electromagnetic field, and benefit the collection of photo-generated carriers. An as-fabricated photodetector (18 A/W) with trans-impedance amplifier circuits can be compatible with the designed high-precision tunable diode laser absorption spectroscopy (TDLAS) gas sensing system. A digital quadrature phase-locked-loop amplifier is used to demodulate the second harmonic (2f) signal for the TDLAS gas sensing circuit, where the circuit exhibits a high detectivity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.138\times 10^{11}$ </tex-math></inline-formula> Jones) and 2800 signal-to-noise ratio (SNR). A good linear relationship is observed between the amplitude of the 2f signal and the CH4 concentration in the range from 100 ppb to 2000 ppm. Our perovskite-based gas-sensing system is quite promising for future infrared trace gas sensing applications, such as medical expiratory gas sensors and greenhouse gas monitoring.

Design of Experimental Circuit Board of Spectrometer Amplifier in Nuclear Electronics

The signal output by a nuclear radiation detector is small in amplitude and irregular in waveform, which needs to be amplified and shaped to measure accurately. Spectrometer amplifiers assume the role of signal amplification and shaping in nuclear radiation measurement instruments, strictly maintaining useful information from the detector output (such as energy information and time information of the rays) and minimizing their distortion during signal processing. According to the needs of undergraduate experimental teaching and nuclear instrument development and application of nuclear electronics courses in nuclear science and technology, this paper designs a flexibly switchable pole zero phase extinction circuit, linear pulse amplification circuit, integral filter forming circuit, and baseline restoration circuit in the experimental circuit board of spectrometer amplifier. The total magnification is about 0 ~ 2040 times adjustable, and the forming time is 0~20μs adjustable. It has the functions of limiting voltage amplitude and optional input and output polarity, which can be adapted to scintillator detectors, proportional counters, Si-PIN, SDD, HpGe and other semiconductor detectors.

Chemiluminescence resonance energy transfer-based multistage nucleic acid amplification circuits for MiRNA detection with low background.

Chemiluminescence resonance energy transfer (CRET)-based assays have shown great potential in biosensing due to their negligible background autofluorescence, yet are still limited by their low sensitivity and short half-life luminescence. Herein, a multistage CRET-based DNA circuit was constructed with amplified luminescence signals for accurate miRNA detection and fixed reactive oxygen species (ROS) signals for cell imaging. The DNA circuit is designed through an ingenious programmable catalytic hairpin assembly (CHA), hybridization chain reaction (HCR), and the use of DNAzyme to realize target-triggered precise regulation of distance between the donor and acceptor for CRET-mediated excitation of photosensitizers. In detail, the analyte catalyzes the hybridization of CHA reactants, which leads to the assembly of multiple HCR-mediated DNAzyme nanowires. Subsequently, DNAzymes catalyze the oxidation of luminol by H2O2, and the adjacent photosensitizer chlorin e6 (Ce6) anchored on the DNA nanostructure is stimulated by the CRET process, resulting in the amplified long-wavelength luminescence and the generation of single oxygen signals through further energy transfer to oxygen. The biomarker miRNA can be detected with great sensitivity by integrating the recognition module into a universal platform. Furthermore, the DNA circuit enables CRET-mediated intracellular miRNA imaging, by detecting singlet oxygen signals through a ROS probe. The significant amplification effect is attributed to the robust multiple recognition of the target and the guaranteed transduction of the CRET signal through programmable engineering of DNA nanostructures. The CRET-based DNA circuit achieves amplified long-wavelength luminescence for accurate miRNA detection with low background and ROS-mediated signal fixation for cell imaging, making it a promising candidate for early diagnosis and theranostics.

Chemical polymerization of conducting polymer poly(3,4-ethylenedioxythiophene) onto neural microelectrodes

Poly(3,4-ethylenedioxythiophene) (PEDOT) is an organic material with good electrochemical activity and electrical conductivity, and it is usually electrochemically deposited on the neural probes to improve their interface properties. However, the workload for electrode modification using an electropolymerization method becomes greater with the increase in the number of electrode channels. Moreover, the integration of electrodes and amplification circuits makes electropolymerization difficult to implement. In this study, a chemical polymerization method was proposed to produce conducting polymer PEDOT on the electrode sites. Compared with electropolymerization, it does not require each electrode site to be connected to a power source. It is competitive in batch preparation and is particularly suitable for neural microelectrodes prepared by a micro-electromechanical systems (MEMS) process. The charge storage capacity, impedance, mechanical stability, and electrochemical stability of conducting polymer PEDOT prepared by the proposed method are evaluated. The results indicate that the method is feasible for batch modification of the microelectrodes, and it is also suitable in cases where energization is inconvenient. • A chemical polymerization method for conducting polymer poly(3,4-ethylenedioxythiophene) modified neural probes is firstly reported. • The proposed modified method is high-efficiency for neural probes with a large amount of electrodes. • The proposed modified method can be conducted on wafer-level, which is compatible with the micro-electromechanical system process. • The electrodes modified with the chemical polymerization method show good electrochemical characteristics.

A novel DNA-quantum dot nanostructure electrochemiluminescence aptamer sensor by chain reaction amplification for rapid detection of trace Cd2.

This work proposes a new enzyme-free electrochemiluminescence (ECL) sensing platform based on a novel DNA-quantum dot (QD) nanostructure and hybridization chain reaction (HCR) amplification for the trace detection of Cd2+. First, the Cd2+ aptamer triggers the HCR amplification circuit, so abundant biotin-labeled DNAs are introduced to the electrode, and then biotin as a linker specifically captures a large number of streptavidin (SA)-CdS QD complexes, showing very high ECL signals. After the present Cd2+ binds to its aptamer on the electrode, it causes the linear DNA structure loaded with a large number of QDs to break away from the electrode, resulting in a significantly decreased ECL response. This method combines the HCR-amplified DNA structure-QD signal with the specificity of the biotin-avidin reaction, enabling the rapid detection of Cd2+ in complex water. Therefore, this sensor provides a novel and competitive strategy for detecting heavy metal ions in actual samples, which extends its application to practical settings, such as environmental monitoring and biomedical diagnostics.

Introduction of an additional source of harmonic signal into the circuit of the electric power resonant amplifier

Problem. The problems of the electric power industry, caused by the depletion of the natural resources of the planet and the need to replace them, initiate the development of new physical and technical solutions with the practical use of the known natural phenomena. Goal. The purpose of this work is to propose to introduce an additional source of a harmonic signal (voltage or current) into the circuit of a resonant amplifier of electric power, to obtain calculated analytical dependencies for numerical estimates of the characteristics of ongoing electromagnetic processes, which make it possible to give a fundamental justification for the real performance of the proposed circuit as a whole, taking into account the interaction of all its functional components. Methodology. This work, ultimately, involves the use of resonant phenomena in circuits with active-reactive elements and their theoretical analysis using the mathematical apparatus of the theory of electrical circuits. Results. It is proposed to implement the resonant amplifier circuit in the form of four active-reactive closed circuits inductively coupled to each other. Moreover, in a practical embodiment, inductive couplings can be carried out using HF ferrites. The first circuit is the input circuit with the harmonic power source to be amplified. The second circuit generates amplified reactive power in the "voltage resonance" mode. The third circuit with an additional harmonic voltage source outputs reactive power from the second circuit in the "current resonance" mode. The fourth circuit, inductively coupled to the third circuit, contains the output load of the entire resonant amplifier. This is a resistor that simulates the release of active power. Originality. Physically, the introduction of an additional source in the third circuit is equivalent to the creation of a "negative active resistance", which makes it possible to create conditions for excitation of current resonance with the minimum possible distortion and, ultimately, to reduce the reverse effect on the amplifying processes in the second circuit (reactive power amplifier). The analysis and numerical evaluation of the characteristics of the proposed scheme of the active electric power resonant amplifier showed its fundamental viability. Practical value. As an example, calculations of currents and voltages in the circuit of an experimental model were made, which enabled to formulate recommendations for the selection of elements of a real active electric power amplifier with high efficiency for low-resistance output loads.

4H-SiC integrated circuits for high-temperature applications

In order to take full advantage of the properties of SiC (silicon carbide) materials at high temperatures, the characteristics of common-source and differential amplifier circuits composed of NMOSFET and PMOSFT based on 4H-SiC have been presented at 25 °C and 300 °C. The characteristics of NMOSFET and PMOSFET based on 4H-SiC are presented from 25 °C to 500 °C. The common-source amplifier displayed gain of 37 dB and GBW (gain–bandwidth product) of 125 kHz at 25 °C. When the temperature increases to 300 °C, the gain decreases to 32 dB and the GBW increases to 600 kHz. The differential amplifier displayed gain of 30 dB and GBW of 25 kHz at 25 °C. When the temperature increases to 300 °C, the gain increases to 34.6 dB and the GBW increases to 130 kHz. Both circuits show good characteristics, indicating that SiC materials and related devices can be applied to high temperature environment.

Method of simulating hybrid STT-MTJ/CMOS circuits based on MATLAB/Simulink

The spin-transfer-torque (STT) magnetic tunneling junction (MTJ) device is one of the prominent candidates for spintronic logic circuit and neuromorphic computing. Therefore, building a simulation framework of hybrid STT-MTJ/CMOS (complementary metal–oxide–semiconductor) circuits is of great value for designing a new kind of computing paradigm based on the spintronic devices. In this work, we develop a simulation framework of hybrid STT-MTJ/CMOS circuits based on MATLAB/Simulink, which is mainly composed of a physics-based STT-MTJ model, a controlled resistor, and a current sensor. In the proposed framework, the STT-MTJ model, based on the Landau–Lifshitz–Gilbert–Slonczewsk (LLGS) equation, is implemented using the MATLAB script. The proposed simulation framework is modularized design, with the advantage of simple-to-use and easy-to-expand. To prove the effectiveness of the proposed framework, the STT-MTJ model is benchmarked with experimental results. Furthermore, the pre-charge sense amplifier (PCSA) circuit consisting of two STT-MTJ devices is validated and the electrical coupling of two spin-torque oscillators is simulated. The results demonstrate the effectiveness of our simulation framework.

Stabilization improvement of the squeezed optical fields using a high signal-to-noise ratio bootstrap photodetector.

High-precision cavity locking is crucial for squeezing optical fields. Here, a bootstrapped low-noise photodetector is utilized in the generation process of the squeezed state of light. This process is based on a combination of a modified trans-impedance amplifier (TIA) circuit and a two-stage bootstrap amplifier circuit. This not only achieves high-precision and long-term stable locking of the optical cavity, but it also improves the degree to which the light field is squeezed. The experiment results show that the detector has a high signal-to-noise ratio (SNR) of 26.7 dB at the analysis frequency of 3 MHz when measuring the shot noise with an injection optical power of 800 µW, and the equivalent optical power noise level is lower than 2.4 pW/Hz in the frequency range of 1-30 MHz. Moreover, the squeezing degree of the quadrature amplitude squeezed state light field can be improved by more than 34.9% when the detector is used for optical cavity locking. The photodetector is useful in continuous variable (CV) quantum information research.

Electrochemical Energy Harvesting Using Microbial Active Matter.

With the continuous growth in world population and economy, the global energy demand is increasing rapidly. Given that non-renewable energy sources will eventually deplete, there is increasing need for clean, alternative renewable energy sources, which will be inexpensive and involve minimum risk of environmental pollution. In this paper, harnessing the activity of cupric reductase NDH-2 enzyme present in Escherichia coli bacterial cells, we demonstrate a simple and efficient energy harvesting strategy within an electrochemical chamber without the requirement of any external fuels or force fields. The transduction of energy has been demonstrated with various strains of E. coli, indicating that this strategy could, in principle, be applicable for other microbial catalytic systems. We offer a simple mechanism of the energy transduction process considering the bacterial enzyme-mediated redox reaction occurring over the working electrode of the electrochemical cell. Also, the amount of energy generated has been found to be depending on the motility of bacteria within the experimental chamber, suggesting possible opportunities for developing microbial motility-controlled small scale power generators. Finally, we show that the Faradaic electrochemical energy harvested is large enough to power a commercial light emitting diode connected to an amplifier circuit. We expect the present study to generate sufficient interest within soft condensed matter and biophysics communities, and offer useful platforms for controlled energy generation at the small scales.

Rancang Bangun Alat Metal Detector dengan Metode Beat Frequency Oscillator

A metal detector using the Beat Frequency Oscillator principle and solenoid induction has been made using a series of tools (IC NE 555, capacitors with values ​​of 3.3 F and 4.7 F, resistors 4.9 kΩ, enamel wire 0.3 mm, 4Ω 3W speakers, and 9V battery). The measuring limit of the tool is obtained through measurements using a metal material, namely iron, where the measured value variables are the value of frequency and voltage Vpp, and the average value of the frequency in the input data after the object is 868.1786 Hz and the average value of the Vpp voltage is 1,427 Volts. While the output data obtained the average frequency value is 863.4895 Hz and the average value of Vpp voltage is 0.325 Volt after the object, as for the sound produced before and after the object the difference is too small, so an amplifier circuit is added using an IC LM386 as Audio Amplifier.

Rancang Bangun Sistem Penampil Suhu Bahan Bakar Reaktor Kartini

The Kartini reactor is a TRIGA-type research reactor with an operating power of 100 kW. The Kartini reactor was built in 1974 and is used for research, irradiation, education, and training purposes. In 2004, this reactor failed to display the fuel temperature in the control room. Therefore, a simple system is made to temporarily show the fuel temperature value while the fuel temperature display in the control room is improved. This system is designed to measure reactor fuel temperatures up to 250 0C. This system consists of an operational amplifier circuit (op-amp), an active low-pass filter circuit, an analog-to-digital converter circuit, and an AT89S51 microcontroller with an LCD circuit. First, the method converts the analog input into a digital value using ADC-0809. Next, the microcontroller's digital data from ADC-0809 is compared with the temperature value of the type K thermocouple. Finally, the temperature value (in 0C) closest to the digital value resulting from the ADC conversion is displayed by the microcontroller via a liquid crystal display. The results of the equipment being made satisfactory are proven by measurements of the Kartini reactor, which was operated for 4.5 hours at a power of 100 kW showing the temperature value on the core in ring B with a value of 117 0C. The voltage vs. temperature table on the K-type thermocouple has validated this temperature value. Keywords: reactor fuel temperature, microcontroller, analog to digital converter.

Signal modulation system measuring device

The design can measure and display other parameters such as the modulation system of the measured signal output by the signal source, identify and display the modulation mode of the measured signal, and output the demodulation signal. The measurement module is composed of an automatic gain amplifier circuit, a broadband amplifier, a low-pass filter circuit, a DDS signal generation circuit, an amplification circuit, and a display circuit. The working principle of the signal modulation measuring device is that the demodulated AM signal is obtained after the spectrum is transmitted by the multiplier, and the high-frequency signal is filtered out by the low-pass filter and amplified by the fixed gain amplifier. After the amplification circuit, the output waveform is sampled by the onboard ADC of MSP432E401Y, and then the fast Fourier transform is performed to obtain various parameters, which are finally displayed on the serial screen.

Application of High-voltage Circuit Breaker Status Evaluation Method Based on Primary and Secondary Integrated Switch Detection Platform

This paper proposes a high-voltage circuit breakers status evaluation method based on the primary and secondary integrated switch detection platform to cope with the poor effect of existing evaluation methods. A high-voltage circuit breaker status evaluation index system was determined in combination with the actual situation of high-voltage circuit breakers. The subjective weight of the status of the high-voltage circuit breaker was determined with the analytic hierarchy process, the objective weight of the status of the high-voltage circuit breaker was calculated by the entropy method, and the analog acquisition accuracy of the high-voltage circuit breaker was improved with the amplification circuit design of the genetic algorithm. After the weight was determined, the overall weighted evaluation was performed, and the status of the high-voltage circuit breaker was evaluated through primary and secondary integration. Through comparative experiments, it can be seen that the results of the weight proportion test on the high-voltage circuit breaker status evaluation based on the primary and secondary integration are greater than that of the traditional high-voltage circuit breaker status evaluation method. Therefore, the designed evaluation method based on the primary and secondary integration can be better applied to the distribution network and protect the circuit.

Identifying incoherent mixing effects in the coherent two-dimensional photocurrent excitation spectra of semiconductors.

We have previously demonstrated that in the context of two-dimensional (2D) coherent electronic spectroscopy measured by phase modulation and phase-sensitive detection, an incoherent nonlinear response due to pairs of photoexcitations produced via linear excitation pathways contributes to the measured signal as an unexpected background [Grégoire et al., J. Chem. Phys. 147, 114201 (2017)]. Here, we simulate the effect of such incoherent population mixing in the photocurrent signal collected from a GaAs solar cell by acting externally on the transimpedance amplifier circuit used for phase-sensitive detection, and we identify an effective strategy to recognize the presence of incoherent population mixing in 2D data. While we find that incoherent mixing is reflected by the crosstalk between the linear amplitudes at the two time-delay variables in the four-pulse excitation sequence, we do not observe any strict phase correlations between the coherent and incoherent contributions, as expected from modeling of a simple system.

Determining Zero Point of Blood Glucose Detection Through Potentiostat Circuit Configuration

Glucose meters have been developed for determining the hyperglycemic and hypoglycemic disorders as well as checking daily glucose levels for diabetic patients. Although multiple commercial glucometers have been presented, the attendance of interferences in the measuring of glucose is still a challenge. This problem can be managed using the proper design of potentiostat as the main part of glucometers. Here, we introduce a novel electrochemical circuit design comprising a microcontroller to specify the optimum zero point for the glucose measuring. The proper configuration of the potentiostat circuit leads to the correct detection of zero point for glucose. For this, the counter electrode (CE) is placed in high impedance mode, as well as the working electrode (WE) and reference electrode (RE) in the feedback path of the transimpedance amplifier circuit. The linear range of the proposed sensor was detected in the concentration ranges of 57–600 mg/dL with a linear equation of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${y}={0.0018} {x}-{0.0693}$ </tex-math></inline-formula> and a sensitivity of 0.0018. The final cost and characteristics of our proposed circuit were better than some other devices.

All Digital Light Processing‐3D Printing of Flexible Sensor

AbstractFlexible sensor with high sensitivity, high durability, and facile fabrication process has promising applications in structural health monitoring, human–machine interface, and soft robotics areas. Digital light processing‐3D (DLP‐3D) printing can print flexible sensor in a scalable process. However, to achieve all DLP‐3D printing of flexible sensor, there still exist challenges of how to print sensing units with high sensitivity to external stimuli, interconnectors with high conductive stability at deformations, and robust interfaces between them for long‐term usage. To address this, a hybrid DLP‐3D printing method is developed, including the key steps of printing carbon nanotube/elastomer (MWCNT/EA) as sensing units and selective electrostatic self‐assembly of silver nanowires (Ag NWs) as interconnectors. As a demonstration, a flexible pressure sensor array integrated with amplifier circuit is fabricated by the method. The MWCNT/EA sensing unit with woodpile structure has nine times improved sensitivity than the solid one. The Ag NW interconnector with serpentine configuration shows insensitivity to strain and good mechanical stability. The interface between sensing unit and interconnector is mechanical robust due to the chemical bond formation under ultraviolet radiation. The flexible sensor could detect external stimuli with enhanced signals enabled by integrated amplifier circuit, exhibiting potentials of the method for flexible electronic fabrication.

A New Design Method for Class-E Power Amplifiers Using Artificial Intelligence Modeling for Wireless Power Transfer Applications

This paper presents a new approach to simplify the design of class-E power amplifier (PA) using hybrid artificial neural-optimization network modeling. The class-E PA is designed for wireless power transfer (WPT) applications to be used in biomedical or internet of things (IoT) devices. Artificial neural network (ANN) models are combined with optimization algorithms to support the design of the class-E PA. In several amplifier circuits, the closed form equations cannot be extracted. Hence, the complicated numerical calculations are needed to find the circuit elements values and then to design the amplifier. Therefore, for the first time, ANN modeling is proposed in this paper to predict the values of the circuit elements without using the complex equations. In comparison with the other similar models, high accuracy has been obtained for the proposed model with mean absolute errors (MAEs) of 0.0110 and 0.0099, for train and test results. Moreover, root mean square errors (RMSEs) of 0.0163 and 0.0124 have been achieved for train and test results for the proposed model. Moreover, the best and the worst-case related errors of 0.001 and 0.168 have been obtained, respectively, for the both design examples at different frequencies, which shows high accuracy of the proposed ANN design method. Finally, a design of class-E PA is presented using the circuit elements values that, first, extracted by the analyses, and second, predicted by ANN. The calculated drain efficiencies for the designed class-E amplifiers have been obtained equal to 95.5% and 91.2% by using analyses data and predicted data by proposed ANN, respectively. The comparison between the real and predicted values shows a good agreement.

Fully GaN Monolithic Integrated Light Emitting Triode‐on‐Bipolar Junction Transistor Device Drivable with Small Current Signals and Its Frequency Response Characteristic: A Modeling and Simulation Study

Intelligent display with multifunctional integration is becoming the frontier and focus of current research on novel display technology. How to realize the single chip integration of lighting with other functions such as switching and driving remain the technical and scientific problems that are desiderated to solve. This article proposes a novel idea of a light‐emitting triode (LET), in which light‐emitting diode (LED) and bipolar junction transistor (BJT) are vertically integrated on a single GaN chip with the same GaN processing. The photoelectrical performances of this “LED on BJT” structure are investigated using finite element simulation. It is verified that LET with electrical–optical modulation and amplification capabilities could be achieved simultaneously. By optimizing the device structure and the doping concentrations of each epitaxial layers, the LET can be operated at a low modulation current injection in the range of tens of microamperes. Therefore, the LET is expected to be directly driven by IC circuits without additional amplifier circuits. Meanwhile, the LET cut‐off frequency can reach more than 80 MHz, allowing the applications of pulse width modulation (PWM) driving and visible light communications.

Design of pH Measuring Equipment for Liquid Waste from Coal Mining Using Arduino Uno

In coal mining, to check the pH content of the water in the liquid waste from coal mining, most of the mining workers use conventional methods, namely by measuring using a digital pH meter or litmus paper periodically. Manual pH reading system makes handling slow. Based on these reasons the researchers designed a tool that can monitor pH values, the working principle of this tool is that the pH electrode is inserted into the sample solution, then the electrode detects the sample solution and changes the electrical signal, where the output will be amplified by an amplifier circuit in the form of an analog voltage, then on Arduino uno analog data is converted to digital data or ADC (Analog To Digital Conversion) after which it is converted again to pH value and displayed on an LCD that has been equipped with I2C. And this tool is also equipped with an RTC (Real Time Clock) so that it can display the time at which pH data is taken in the waste. The results of the calibration of the pH sensor obtained a linear equation, namely, Y = 25.84 - 7.1211X so that the designed tool has an error percentage of the manufacturer's pH meter tool of 1.028 %. By using this tool, the writer concludes that 0.4 grams of camphor (CaO) on the prototype or 480 kg in real conditions with a pool area of 600 m^3 can reduce the output voltage on the pH sensor from 3.20 V to 2.56 V thereby increasing the pH value. from 3.07 to 7.58 in pool 4 or drain pool.