Operational Amplifier Circuit Research Articles

Automatic Power Factor Compensation (APFC) for Industrial Power Use to Minimize Penalty

Abstract: In this proposed system, two zero crossing detectors are used for detecting zero crossing of voltage and current. The project is designed to minimize penalty for industrial units using automatic power factor correction unit. The microcontroller used in this project belongs to 8051 family. The time lag between the zero-voltage pulse and zero-current pulse is duly generated by suitable operational amplifier circuits in comparator mode is fed to two interrupt pins of a microcontroller. The program takes over to actuate appropriate number of relays from its output to bring shunt capacitors into load circuit to get the power factor till it reaches near unity. The capacitor bank and relays are interfaced to the microcontroller using a relay driver. It displays time lag between the current and voltage on an LCD. Furthermore, the project can be enhanced by using thyristor control switches instead of relay control to avoid contact pitting often encountered by switching of capacitors due to high in rush current

Optimal control for continuous-time Markov jump singularly perturbed systems : A hybrid reinforcement learning scheme

This article discusses the adaptive optimal control problem for continuous-time Markov jump singularly perturbed systems with unknown system dynamics. First, the subsystems transformation technique is introduced to reconstruct the system with stochastic jump characteristics, yielding a set of parallel subsystems. Next, under the framework of reinforcement learning, an offline model-based hybrid iteration algorithm is developed to approximate the solution of the full-order coupled algebraic Riccati equations. Following this, to escape from the system model constraints, an online model-free hybrid iteration algorithm is introduced and relevant convergence proof is given. Compared to traditional value iteration and policy iteration algorithms, the hybrid iteration algorithm has ideal convergence rate and eliminates the requirement of initial stabilizing control policy. At the end, the availability of the online algorithm is demonstrated by means of an operational amplifier circuit model as a simulation example.

Farmer Friendly Solar Based Electric Fence for Rural Agriculture

Agriculture provides all the people’s food needsas well as a variety of raw materials for industry. However, there is a significant loss of crops due to animal intrusion in agricultural lands. Wild animals will wreak havoc on crops. As a result, it’s critical to keep an eye out for animals in the region. Then various devices should be activated to repel the dangerous animals. Operational amplifier circuits are put in place primarily for the purpose of detecting animal intrusion into the farm. The completed protection system is responsible for providing early warning of potential wild animal intrusion and harm. Key Words: agriculture operational amplifier circuits farm

The Design of Low Power Op-amp for Biomedical Application

This work presents a low-power operational amplifier (op-amp) circuit design which optimized and tailored specifically for biomedical circuit application in low power environment. The proposed op-amp design incorporates the folded cascode differential amplifier technique with a low voltage supply 1.2 V, utilizing current biasing, current mirrors, and adopted low-power circuit topologies. AC and DC analysis are carried out to analyse the performance of the proposed design. Extensive simulations executed using industrial standard EDA tool have validated the circuit design, and demonstrated a gain of 70.94 dB, UGBW of 4.90 MHz, GM of 52.70 dB, PM of 82.02 degrees, PSRR of 82.77 dB, CMRR of 100.78 dB, and total power dissipation of only 28.07 mW. Low power consumption is essential for biomedical circuit applications, and the result shows a significant power reduction without compromising other performance parameters. The proposed op-amp circuit design is suitable to be implemented in low-power and high-performance biomedical devices.

Analysis of Two Stage CMOS Operational Amplifier in 90nm CMOS Technology

Abstract: Operational amplifier circuits are used in computation, instrumentation and other applications. Precision op-amps previously used in instrumentation are now-a-days being used in industrial and automotive applications. Hence, there always exists a need for better precision op-amps. It should operate under a wide temperature range. Nowadays, due to the industry trend of applying standard process technologies to implement both analog circuits and digital circuits on the same chip, Complementary Metal-Oxide Semiconductor (CMOS) technology has become dominant over bipolar technology for analog circuit design in a mixed-signal system. Two-stage Op-Amp is one of the most commonly used Op-Amp architectures. In this work an operational amplifier based on CMOS is presented whose input depends on its bias currents which is 20µA and designed using 180nm and 90nm technologies. In sub-threshold region due to unique behavior of the MOS transistors not only allows a designer to work at low voltages and it also allows operating at low input bias currents. Most CMOS Op-Amps are designed for specific on-chip applications and are only required to drive capacitive loads of a few pf. In this proposed work, design of a two stage fully differential CMOS operational amplifier is presented and simulations are carried out in 180nm and 90nm technologies for various parameters. The simulation is to be carried out using Cadence Virtuoso Tool.

Signal dynamic range expansion and power supply voltage reduction for an exponentiation conversion IC

In order to compensate for the non-linearity of an electronic device, an exponentiation conversion circuit that can change the power exponent to any value has been proposed. The exponentiation conversion circuit multiplies the logarithmically converted input signal by a power exponent value to perform exponential conversion. As a result, we can obtain the power function characteristic of a power exponent value. This circuit is a small-scale circuit that utilizes the exponential characteristics of the MOSFET subthreshold region. In a conventional circuit, expansion of the signal dynamic range and reduction of the power supply voltage have been an issue. In this paper, it was confirmed by simulation that the signal dynamic range has expanded by optimizing the current density of MOSFETs. In addition, the linearity of the multiplying circuit was improved by feedback produced by the operational amplifier circuits. We proposed reducing its power supply voltage from 6.0 to 3.3 V by a new multiplying circuit that can eliminate the restriction of maximum voltage gain. Our circuit expands its signal dynamic range from 17.5 to 42.7 dB in condition of the power exponent value from 0.50 to 2.0.

A 65 nm CMOS rail-to-rail auto-zero operational amplifier based on charge pump internal power supply

A high-gain, low-offset, and low-power auto-zero operational amplifier with rail-to-rail input/output is proposed. Based on a time-interleaved charge pump high-voltage on-chip internal power supply, the PMOS differential pair input configuration will achieve a rail-to-rail input range with constant transconductance. Time-interleaved auto-zero continuously eliminates the input offset voltage of the operational amplifier in the time domain. An nA-level bias circuit to realize low power. The operational amplifier circuit is based on a 65 nm CMOS process. Under 1.2V power supply voltage and temperature 27 °C, the input offset voltage of the operational amplifier is 3.16 μV and the input offset current is less than 20 pA. The temperature drift coefficient of offset voltage is 0.005 μV/°C between −40 °C and 90 °C. The variation rate of input transconductance is only 5.6 % among the rail-to-rail input range. The equivalent DC gain is 106.4 dB, the unit gain bandwidth is 0.54 MHz, the phase margin is 76.5°, and the power consumption is about 0.19 mW. The layout area is 0.83 × 0.75 mm2.

Innovative Design and Application Analysis of Integrated Operational Amplifiers

Operational amplifiers in integrated circuits come in many varieties and numbers and are an essential part of electronic systems. Its performance directly affects the accuracy and effectiveness of the whole system. As the market demand for operational amplifiers in different fields is growing day by day, according to different kinds of demand, people have designed a variety of operational amplifier structure. This paper describes the basic characteristics of operational amplifiers and analyzes three basic structures that are extremely relevant for modification circuits. The common-source, common-gate circuit structure op-amp has the advantages of high gain, high input common-mode range, high output swing, and high overall gain bandwidth, so it has been adopted as the most commonly used architecture today and in the future. The current improvements in operational amplifier design are mainly focused on two-stage operational amplifiers, and less on multi-stage operational amplifiers. The folded common source and common gate operational amplifier circuits are characterized by good frequency characteristics, comparatively low power consumption and high bandwidth per unit gain. The demands on the performance of operational amplifiers will become higher and more varied, and more excellent improved circuits are needed.

Intelligent Optimization of CMOS Operational Amplifier Using 3D Ant Colony Optimization

This paper presents the use of an artificial intelligence (AI) tool based on ant colony behavior to design an operational amplifier circuit. The ant colony optimization (ACO) is implemented in a hybrid evolutionary sizing method to automate analog circuit design. This new meta-heuristic approach that combines the artificial intelligence of an ant colony and the 3D matrix method is developed to determine the optimal dimensions and the main influencing performances of fundamental analog circuits and, including operational amplifiers (op-amps). The proposed methodology uses ACO and Cadence Spectre as dimensioning techniques and implementation platform, respectively. The Three Dimensions (3D) ACO algorithm is successfully used for analog circuit sizing, and the obtained results demonstrate its effectiveness in sizing basic and more complicated analog circuits.

Evolutionary Optimization Techniques in Analog Integrated Circuit Designs

The proposed genetic algorithm (GA) and particle swarm optimization (PSO) applied for the optimal design of a one-stage operational amplifier circuit with a current mirror load are studied in this work. The sizes of transistors are optimized using the proposed GA and PSO for improved areas and performance parameters of the circuit. A number of performance parameters are collected from the data set created by GA and PSO to optimize the size of transistors and other design parameters. The Spectre simulator is chosen for the simulation of circuit parameters to obtain necessary for the GA and PSO algorithm. Post-optimization results justify that the proposed GA and PSO methods are competitive with differential evolution regarding convergence speed, design specifications, and the optimal CMOS one-stage operational amplifier circuit parameters.

Experimental comparison of operational amplifier and voltage sensor-based zero-crossing detector circuits for power electronic converters

Abstract Zero-crossing detection (ZCD) circuits are widely utilized to synchronize power electronics converters with the grid and measure frequency and phase angle. They are usually designed using an operational amplifier (op-amp) or a voltage sensor accompanied by a processing device. The performance profile of these circuits alters depending on many factors, including the input voltage level. An experimental comparison between the two ZCD circuits across various input voltage levels does not appear to be presented in the literature. This work experimentally compares the performance of an op-amp and an isolated voltage sensor-based ZCD circuits, considering their rise/fall latency and precision in detecting the zero-crossing points (ZCPs). The design process and the experimental results demonstrated that the op-amp-based ZCD circuit is susceptible to false and multiple detections of ZCPs and is best suited for relatively low-voltage applications. On the other hand, the voltage sensor-based ZCD circuit allows signal conditioning and is best suited for relatively high voltage applications.

A HCI-hardened self-healing operational amplifier circuit

In this paper, a self-healing operational amplifier circuit to deal with hot carrier injection (HCI) effect is proposed. An inverter-based operational amplifier is implemented. The influence degree of HCI effect to performance of the operational amplifier is studied which utilizes an equivalent circuit model of HCI effect. A monitoring circuit is proposed to monitor the degree of HCI degradation. A charge pump circuit is utilized to generate a corresponding voltage according to the result of monitoring circuit. The output voltage of the charge pump circuit is feedback to tune the substrate voltage of the operational amplifier (and the monitoring circuit) to mitigate degradation. The simulation results show that the self-healing operational amplifier can maintain the performance at low temperature and room temperature for 50 years (and high temperature for 30 year) under HCI effect. The gain of the inverter-based operational amplifier without self-healing is reduced from 45 dB to 9.6 dB after 50 years, and the gain of the self-healing operational amplifier will maintain at about 46 dB among 50 years. The influence of HCI effect on bandwidth and phase margin is less than that of temperature and process corner. The lifetime of self-healing operational amplifier circuit is >5 times longer than lifetime of based on inverter operational amplifier circuit without self-healing. In addition, the self-healing operational amplifier is robust to process corner.

A 0.8 V, 14.76 nVrms, Multiplexer-Based AFE for Wearable Devices Using 45 nm CMOS Techniques.

Wearable medical devices (WMDs) that continuously monitor health conditions enable people to stay healthy in everyday situations. A wristband is a monitoring format that can measure bioelectric signals. The main part of a wearable device is its analog front end (AFE). Wearables have issues such as low reliability, high power consumption, and large size. A conventional AFE device uses more analog-to-digital converters, amplifiers, and filters for individual electrodes. Our proposed MUX-based AFE design requires fewer components than a conventional AFE device, reducing power consumption and area. It includes a single-ended differential feedback operational transconductance amplifier (OTA) and n-pass MUX-based AFE circuits which are related to the emergence of low power, low area, and low cost AFE-integrated chips that are required for wearable biomedical applications. The proposed 6T n-pass multiplexer measures a gain of -68 dB across a frequency range of 100 kHz with a 136.5 nW power consumption and a delay of 0.07 ns. The design layout area is approximately 9.8 µm2 and uses 45 nm complementary metal oxide semiconductor (CMOS) technology. Additionally, the proposed single-ended differential OTA has an obtained input referred noise of 0.014 µVrms, and a gain of -5.5 dB, while the design layout area is about 2 µm2 and was designed with the help of the Cadence Virtuoso layout design tool.

Asynchronous Event-Triggered-Based Control for Stochastic Networked Markovian Jump Systems With FDI Attacks

In this article, a new asynchronous event-triggered-based output-feedback control method is proposed for a special type of networked Markovian jump systems susceptible to network delays and attacks. A novel controller is designed to make allowances for four cases that are common in practical situations: 1) a network delay; 2) false data injection (FDI) attacks; 3) asynchrony between system modes and controller modes; and 4) an event-triggered scheme. First, to avoid traditional assumptions about system delays, a novel Lyapunov function is proposed, based on which a new stability theory is formulated to guarantee exponential stability. Second, an FDI attack is represented as a stochastic process, which can be dealt with properly by the designed controller. Third, a new delay-based event-triggered scheme is brought into the controller design to reduce the network bandwidth consumption and save the network transmission resources. Then, an asynchronous controller is engineered with the aid of a hidden-Markov model, which can extend the application scope of the proposed method. Note that we put the above four factors into one framework, which implies a co-design of an anti-attack controller and an event-triggered scheme is developed. Finally, an operational amplifier circuit is simulated to verify the feasibility and superiority of the designed controller.

Signal Processing Design for Wide Bandwidth Hybrid Current Sensor based on Enhanced Analog Operational Amplifier Circuit

Signal Processing Design for Wide Bandwidth Hybrid Current Sensor based on Enhanced Analog Operational Amplifier Circuit

A Novel Carbon Nanotube Field Effect Transistors Based Triple Cascode Operational Transconductance Amplifier: An Optimum Design

This paper discusses a triple-cascode operational transconductance amplifier (TCOTA) circuit’s design and modeling. These proposed TCOTAs are constructed using 45 nm Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) and Carbon Nanotube Field Effect Transistors (CNTFETs). At the 45 nm technology node, three distinct varieties of CNT-based TCOTAs have been designed and contrasted with conventional CMOS-based TCOTAs. The performance of the CNT-based TCOTAs, particularly a pure CNT-TCOTA, has significantly improved, according to the assessment of the fundamental aspects of all the devices. The DC gain has been enhanced by 73% when contrasting the pure CNT-TCOTA to the conventional CMOS-TCOTA, the CMRR has improved by 28%, and the power consumption has been reduced by 100.63%. Furthermore, in pure CNT-TCOTA, (FOM)1 and (FOM)2 have increased by 194% and 173%, respectively. It has also been investigated thoroughly how CNT-based OTAs perform by adjusting the CNT diameter (DCNT), pitch (S), and number of CNTs (N) at CL = 0.01 pF and 0.9 V power supply. It has been determined that using optimum CNT quantity, the pitch between CNTs, and diameter values can further enhance their performance. The simulation and comparative studies of all circuit structures have reported that novel and remarkable improvement is distinguished in CNT-based TCOTA. According to simulation and comparative assessments of all circuit structures, CNT-based TCOTA exhibits a novel and noteworthy improvement. Moreover, when compared to the conventional CMOS-TCOTA, the pure CNT-TCOTA has shown significant enhancement of 11.1% and 10.24% in GM and PM, respectively. Pure CNT-TCOTA has been demonstrated to be highly stable by the stability analysis.

Research on portable constant pulse current source device

A set of portable constant pulse current sources with STM32 as the control core is developed, which mainly involves the SCM control module, operational amplifier circuit module, pulse output module, power module, key module, and display module. Based on the traditional constant-current source circuit design, the real-time display control system is constructed by software programming optimization, which has the characteristics of portable and strong stability. By connecting the field effect tube and operational amplifier in series to form a feedback loop, the current output accuracy is improved and the stability of the current output is ensured. The experimental results show that after the op-amp circuit is introduced into the series feedback system, the front and rear order circuit can be more stable, and ensure the reference voltage is stable at the same time, through the duty cycle of PWM wave to adjust the current output, so that the constant current source output 0~2mA adjustable low-frequency stable current. At the same time, in terms of human-computer interaction, in addition to the use of buttons to adjust the current at both ends of the load, a small OLED display screen is used to display the current, voltage, and pulse frequency in real time. The experiment shows that the instrument has high stability and load adaptability, and has high practical value.

Performance analysis of CMOS based analog circuit design with PVR variation

Process, supply voltage, and temperature (PVT) are three important factors which contribute to performance variation of the complementary metal–oxide–semiconductor (CMOS) based analog circuits. In this paper, CMOS based analog circuit design with the PVT variation effects are explored. The effects of the PVT variation on the performance of CMOS based analog circuits are introduced. The optimization of CMOS based analog circuits such as differential amplifier (DA) and two-stage operational amplifier (op amp) circuits with PVT variations with different algorithms such as cockoo search (CS), particle swam optimization (PSO), hybrid CSPSO, and differential evaluation (DE) algorithms is presented. Each algorithm is implemented using the C programming language, interfaced with Ngspice circuit simulator, and tested on the Intel®core™ i5, 2.40 GHz processor with 8 GB internal RAM using the Ubuntu operating system (OS). The result shows PVT variation affects the performance of CMOS circuit.

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.

A TRIZ-Adopted Development of a Compact Experimental Board for the Teaching and Learning of Operational Amplifier with Multiple Circuit Configurations

Operational amplifiers (op-amps) are generally used for actualizing simple and complex electronic circuits in the subject of analogue electronics. In an effort to improve the teaching of op-amps in electronics engineering curricula, op-amp circuits in various configurations are often used for experiments in laboratory sessions so that students can acquire certain psychomotor and cognitive skills by constructing circuit connections and analyzing input–output waveforms. As a result, multiple configurations of operational amplifier circuits are often needed, requiring multiple sets of experimental boards or circuits for each experiment. This is usually not cost effective, requires more consumable electronic components, requires more maintenance and storage space in facilities, and is less user friendly for the students. Therefore, the aim of this research is to design a single, compact, and easy-to-replicate experimental board that can be converted into multiple configurations of the LM741 operational amplifier, comprising an inverting amplifier, a noninverting amplifier, a voltage follower, a summing amplifier, a differential amplifier, a differentiator, and an integrator, with minimal electronic components at a cost lower than EUR 10. The experimental board was tested with a constant input voltage of 1.0 V AC and a switching frequency of 1.0 kHz. It is capable of producing an output voltage corresponding to the individual operational amplifier configurations and can thus be used as a facilitating module for teaching and learning activities in the field of analogue electronics.