Current Amplifier Research Articles

A 60 dB gain range programmable gain current amplifier for ultrasound sensing

This article presents a programmable gain current amplifier (CA) for ultrasound sensing applications. The design proposed consists of a current divider and a close-loop current amplifier. The CA utilizes switches to adjust the resistance of the shunt resistors and feedback resistors to achieve variable gain, thus realizing the time gain compensation (TGC) function. The proposed CA implemented in 180-nm BCD technology occupies an active area of 0.059 mm2. Measurement results show that the CA achieves a maximum gain of 36.6 dB and a gain range of 60 dB. The average input-referred noise spectral density is 0.32 pA/√Hz at maximum gain condition while consuming a power of 1.07 mW.

Fourth‐order inverse filter configuration using current differencing buffered amplifier

AbstractThis article presents three different higher‐order inverse filter (IF) configurations using current differencing buffered amplifier (CDBA) as an active component and a few passive elements. The topology can be used to synthesize fourth‐order inverse low pass filter (FO‐ILPF), inverse band pass filter (FO‐IBPF), and inverse all‐pass filter (FO‐IAPF) using suitable admittance combinations. PSPICE simulations verify the functionality of the proposed IFs with the CMOS‐based CDBA using 180 nm technology. The theoretical analysis and simulated results are also carried out, which shows that they are in close agreement. The passive sensitivity analysis, non‐ideality analysis, Monte Carlo simulation, temperature analysis, percentage of total harmonic distortion (%THD), and noise analysis of the proposed filters are also performed. The proposed design has also been implemented using the current feedback operational amplifier (CFOA) as IC AD844AN to verify the functionality.

Development of an Electronic Photo Sensor for Chlorophyll Detection

The amount of chlorophyll in plant leaves can be measured using time-consuming and challenging traditional chemical procedures; alternatively, highly expensive sensor-based meters are available in the market. In this paper, the design of an inexpensive, less complex, optimum-sized ESP-32-based electronic chlorophyll reader is presented. For the suggested electronic reader the design of the photosensor circuit is the primary focus of the study. It includes designing current amplifier circuits for photodetectors and LED driver circuits for red and infrared LEDs. Spectral absorption by leaf chlorophyll is the parameter used for measuring chlorophyll. Regarding leaf chlorophyll spectral absorption, red LEDs are the most absorbing. Utilizing this function, red LED spectrum absorption measurements are made for various plant leaves. The chlorophyll content of the same leaves is then determined in the botany lab using Arnon's method. To confirm the photosensor design, the red LED spectrum absorbance and the chlorophyll identified using Arnon's technique are analyzed for different leaves. The photosensor is verified to be operating correctly. Additionally, a linear regression model for performance analysis is provided.

A Fast Transient LDO Regulator Featuring High PSRR Over 100-kHz Frequency Range With Adaptive, Dynamic Biasing, and Current Mode Feed-Forward Amplifier

A Fast Transient LDO Regulator Featuring High PSRR Over 100-kHz Frequency Range With Adaptive, Dynamic Biasing, and Current Mode Feed-Forward Amplifier

Design of fractional-order transitional filters of the Butterworth-Sync-Tuned, Butterworth-Chebyshev, and Chebyshev-Sync-Tuned types: optimization, simulation, and experimental verification

This paper presents the optimal and generalized design of three different fractional-order (FO) transitional filters for the first time in the literature. The transitional filters considered are of the FO Butterworth-sync-tuned, the FO Butterworth-Chebyshev, and the FO Chebyshev-sync-tuned types. A metaheuristic swarm intelligence optimizer, namely the Crow Search Algorithm (CSA), helps to achieve the optimal FO filter model that minimizes the magnitude error with the theoretical function. The accuracy of the proposed approximants is examined for 19 different combinations of orders of the constituent filters for each of the three types of FO transitional filters. Comparisons with the modified stability boundary locus-based second-, third-, and fourth-order filter approximants demonstrate the compactness and superior accuracy of the proposed models. The average performance regarding the approximation accuracy, computational time, and convergence of CSA for solving the proposed filter design problems is investigated. Circuit simulations conducted on the OrCAD PSPICE platform for the proposed filter using the current feedback operational amplifier as an active element highlight good matching between the proposed model and theoretical filter function. Experimental validation is also carried out to justify the practical feasibility of the proposed filter with printed circuit board fabricated FO capacitor emulators.

Nature inspired algorithm based design of near ideal fractional order low pass Chebyshev filters and their realization using OTAs and CCII

Fractional order filters offer greater freedom of design and a precise control over stopband attenuation in electronic circuits and systems. This paper presents the design of a fractional order low pass Chebyshev filter (FOLCF) that achieves near-ideal response characteristics. The methodology introduced utilizes metaheuristic optimization methods, including particle swarm optimization, firefly algorithm, and grey wolf optimization. These techniques are employed to precisely adjust the filter coefficients for the orders (1+α), (2+α), and (3+α). The adjustment is carried out by comparing the desired behaviour of the FOLCF with generalized fractional order low pass transfer functions. Throughout these instances, the parameter α is varied within the range of (0, 1). The designed filters are then tested and compared on the basis of various factors. Simulation results demonstrate that the designed filters closely follow the behaviour of an ideal Chebyshev filter with maximum passband and stopband magnitude errors being −31.93 dB and −52.74 dB respectively for (1+α) order filters. These values for (2+α) and (3+α) order FOLCF have been observed to be −30.04 dB and −55.91 dB; −17.72 dB and −49.52 dB respectively. Furthermore, it has been observed that the proposed work outperforms existing state-of-the-art approaches in various aspects, including magnitude error, stopband attenuation, and cut-off frequency. The stability of the designed filters has been verified through stability analysis. Additionally, practical feasibility of the proposed FOLCF is demonstrated through SPICE simulations for α = [0.2,0.5,0.8] using second generation current conveyor (CCII) and operational transconductance amplifier (OTA) based topologies while approximating the constant phase element using fifth order continued fraction expansion. The SPICE implementations closely follow the behaviour of ideal filter with −48.67 dB and −62.8 dB as mean square errors for CCII and OTA circuits respectively, showcasing the proposed filters' superiority and practical applicability in advanced electronic design.

Design of Lossless Negative Capacitance Multiplier Employing a Single Active Element

In this paper, a new negative lossless grounded capacitance multiplier (GCM) circuit based on a Current Feedback Operational Amplifier (CFOA) is presented. The proposed circuit includes a single CFOA, four resistors, and a grounded capacitor. In order to reduce the power consumption, the internal structure of the CFOA is realized with dynamic threshold-voltage MOSFET (DTMOS) transistors. The effects of parasitic components on the operating frequency range of the proposed circuit are investigated. The simulation results were obtained with the SPICE program using 0.13 µm IBM CMOS technology parameters. The total power consumption of the circuit was 1.6 mW. The functionality of the circuit is provided by the capacitance cancellation circuit. PVT (Process, Voltage, Temperature) analyses were performed to verify the robustness of the proposed circuit. An experimental study is provided to verify the operability of the proposed negative lossless GCM using commercially available integrated circuits (ICs).

CC-CBTA-Based Floating Inductance Simulator with CM/VM PID Controllers

This work describes voltage-mode (VM), current-mode (CM) PID controllers and an electrically controllable floating inductance (FI) simulator circuit. Only a single current-controlled current backward transconductance amplifier (CC-CBTA) and a grounded capacitor are used in the proposed FI simulator circuit. One CBTA, one CC-CBTA, two capacitors and one resistor are used in the proposed PID controllers. All of the proposed circuits have appropriate input and output impedance values, allowing them to be utilized in cascade connections without requiring a buffer circuit. There is also no matching constraint between the active and passive values of the proposed circuit. The SPICE software environment and experimental results were used to validate theoretical derivations and associated outcomes. The layout of the CC-CBTA has been built, and the post-layout simulations are carried out using the netlist extracted from the layout. Comparisons were made with similar circuits found in the professional literature.

New Z copy- current differencing transconductance amplifier active filter using FinFET transistor based current Mode Universal Filter

This research paper presents the design of an active current mode device named Z-copy- Current Differencing Transconductance Amplifier (ZC-CDTA) in conjunction with FinFET (Fin Field-Effect Transistor) transistors. An input bias current can be used to adjust its parasitic resistances at its two current input ports. It is ideal for use in current-mode signal processing, which is steadily more common than voltage-style signal processing, because it operates in current mode on all terminals. The suggested component was implemented using Finfet technology, and its performances were assessed using simulations using cadence tools and linear technology SPICE. They demonstrate the new active element's usage, with a maximum bandwidth of 300MHz. The highest power consumption is 1.01 mW, and the supply voltages can be as low as ±0.1 V. The low-power consumption and wide current range tuning of the suggested Zc-CDTA are achieved.

Исследование точности определения места повреждения воздушных линий по данным от устройств синхронизированных векторных измерений различных классов и производителей

The technology of synchronized phasor measurements has been widely used in the Russian power system to analyze the parameters of steady-state electrical power modes and to record electro-mechanical transient processes. Issues on fault location based on synchronized phasor measurements have mainly been discussed in foreign publications. A significant drawback of most research papers on this issue is simplified modeling of both overhead lines and current and voltage measurement channel as well as digital filters of phasor measurement units (PMUs). The goal of this research is to develop a fault location algorithm based on synchrophasor measurements and to study its accuracy by using specialized equipment including a real-time digital simulator (RTDS), PONOVO current and voltage amplifiers and production-grade PMUs. A PMU-based double-ended fault location algorithm is developed using long-line equations and well-known electromagnetic transient theory concepts. Currents and voltage oscillograms of both overhead transmission line ends are modelled in the MATLAB/Simulink software package. These oscillograms are saved as COMTRADE files and played back using the RTDS hardware and all-in-one software package RSCAD. In addition, the study uses two production-grade PMUs, the first one is TPA-02, and the second one is a merging unit ENMU acting as a PMU, thus imitating PMUs at the line terminals. To time-align all the measurements and to aggregate PMU data frames, various auxiliary software such as PMU Connection Tester, and hardware is used. A double-ended fault location (FL) method utilizing synchrophasors under a fault has been developed. The method is based on an overdetermined system of nonlinear equations that describes physical processes in an overhead power line and can be applied under various fault types. An integrated study of the efficiency of the developed FL method has been conducted. FL errors have been computed using production-grade PMUs ENMU and TPA-02, along with the RTDS and other equipment. The authors have considered the case of configuring PMUs of different classes at the overhead line terminals, and different phasor reporting rates as well. The conducted experiments make it possible to reveal that the fault location errors do not exceed the thresholds imposed by the standard STO 56947007-29.120.70.241-2017 in 88 % of all the analyzed fault scenarios. The developed FL method makes it possible to achieve the accuracy required by regulatory guide in calculating the distance to the short circuit point in most of the cases examined. Based on the results of numerical experiments for various types of fault cases, it can be concluded that the PMU class and phasor reporting rate do not have a significant impact on the FL accuracy, provided that the fault duration is enough for the PMU filter to approach a steady output.

Electronically Tunable Sinusoidal Oscillator Using Only Single Current-Controlled Current Conveyor Trans-Conductance Amplifier

This work presents a wide frequency range sinusoidal oscillator design that relies on only one active component, a current-controlled current conveyor trans-conductance amplifier, and a few passive components. It just employs two grounded and non-floating capacitors and one resistor to complete the procedure. This design has the advantage of allowing the oscillation frequency and condition to be adjusted not only electronically, but also separately, without affecting the values of any passive components. To verify the functionality and usefulness of the developed sinusoidal oscillator circuit, ORCAD PSPICE simulations are done using 0.18 um process parameters for complementary metal oxide semiconductor technology. The obtained results demonstrate its application to a wide range of frequency generation without the need for additional components, hence validating the theoretical expectation.

Broadband coplanar-waveguide-based impedance-transformed Josephson parametric amplifier

Quantum-limited Josephson parametric amplifiers play a pivotal role in advancing the field of circuit quantum electrodynamics by enabling the fast and high-fidelity measurement of weak microwave signals. Therefore, it is necessary to develop robust parametric amplifiers with low noise, broad bandwidth, and reduced design complexity for microwave detection. However, current broadband parametric amplifiers either have degraded noise performance or rely on complex designs. Here, we present a device based on the broadband impedance-transformed Josephson parametric amplifier that integrates a hornlike coplanar waveguide transmission line, which significantly decreases the design and fabrication complexity while keeping comparable performance. The device shows an instantaneous bandwidth of 700 (200) MHz for 15 (20) dB gain with an average input saturation power of −110 dBm and near quantum-limited added noise. The operating frequency can be tuned over 1.4 GHz using an external flux bias. We further demonstrate the negligible backaction from our device on a transmon qubit. The amplification performance and simplicity of our device promise its wide adaptation in quantum metrology, quantum communication, and quantum information processing. Published by the American Physical Society 2024

Voltage-Mode Multifunction and Universal Biquads with Two CFOAs

In this paper, a new voltage-mode (VM) multifunction filter including only two grounded capacitors, three resistors, and two current feedback operational amplifiers is introduced. This filter with one high input impedance and two low output impedances can simultaneously provide band-pass filter (BPF) and low-pass filter (LPF) responses with an adjustable gain. A universal VM filter topology with three inputs and one output generating high-pass filter (HPF), BPF, LPF, notch filter, and all-pass filter (APF) responses is obtained from the multifunction one. It has the same number of active and passive elements as the multifunction and a low output impedance. Sensitivities of both introduced filters are low enough. However, the APF of the introduced universal filter has a passive element-matching problem. As an example, parasitic impedance effects are considered for the LPF of the universal filter, while non-ideal gain analyses are given for the HPF. To see how the introduced universal filter works, countless simulations are performed through the SPICE (Simulation Program with Integrated Circuit Emphasis) program in which 0.13 [Formula: see text]m IBM CMOS technology parameters are utilized. DC supply voltages are selected as ± 0.9 V. Also, several experiments using commercially available AD844s with ± 10 V supply voltages are carried out to see the performance.

Study of MOS and IGBT transistors at switching with variable duty cycle

In this paper, the functionality of MOS and IGBT transistors is examined under identical working conditions, both in terms of command frequency and load circuit. A variable duty cycle and variable frequency signal generator is used to control transistors. Various electronic components and Arduino-UNO modules, as well as the 16×2 LCD screen, were used to create the signal generator. The control signal is amplified by a current amplifier to adapt the output voltage to the value required to control the transistors. The operation of MOS and IGBT transistors at various operating frequencies with resistive or inductive loads is compared. Thus, the communication times of the transistor capsules were determined at various operating temperatures. The temperature was determined indirectly by connecting a thermistor to the transistor capsule.

On Approach to Increase Density of Fieldeffect Heterotransistors in the Framework of a Current Follower Transconductance Amplifier. Influence of Mismatchinduced Stress and Porosity of Materials on Technological Process

In this paper we introduce an approach to increase density of field-effect heterotransistors in the framework of a current follower transconductance amplifier. In the framework of the approach we consider manufacturing the amplifier in heterostructure with specific configuration. Several required areas of the heterostructure should be doped by diffusion or ion implantation. After that dopant and radiation defects should by annealed framework optimized scheme. We also consider an approach to decrease value of mismatch-induced stress in the considered heterostructure. We introduce an analytical approach to analyze mass and heat transport in heterostructures during manufacturing of integrated circuits with account mismatch-induced stress.

A novel self-powered triboelectric sensor for early waring of lubrication failure

In tribology, maintaining good lubrication of friction pairs is an important technical means to reduce wear and failure, which is very important but difficult to monitor the lubrication state of friction pairs. In this paper, when measuring the thickness and shape of the lubricating oil film by the ball-disk elastohydrodynamic oil film measuring instrument, a current amplifier is integrated to measure the electrical signal generated during the friction process. By monitoring the change of lubricating oil film, the change of ball-disk friction force, and the change of triboelectric signal during the friction process in real time, the relationship between the tribological behavior and the triboelectric behavior of the friction pair is explored. The experimental results show that under the conditions of limited oil supply, different rotational speeds and different lubricating oil viscosities, the time of the discharge phenomenon of the steel ball corresponds one-to-one with the time when the friction pair starts to wear under oil-scarce lubrication. The discharge occurs due to the electric charge breaking through the air in the micro-gap of the wear scar. The results demonstrate that the formation of the oil-depleted state has an important influence on the triboelectric process. Based on the relationship between the two, the state of the lubricating oil can be reflected in real time by using the triboelectric signal, which provides a reliable method for the real-time monitoring of the lubrication state.

Current feedback operational amplifier‐based fully orthogonal universal and multifunction filters

SummaryThis paper introduces a second‐order voltage‐mode (VM) multiple‐input single‐output (MISO) universal filter and a second‐order current‐mode (CM) single‐input multiple‐output (SIMO) multifunction filter. The introduced VM MISO universal filter includes a single current feedback operational amplifier (CFOA) and a single voltage follower as active elements, while the introduced CM SIMO multifunction filter contains two CFOAs. Both introduced circuits are orthogonally controllable. In other words, the quality factors can be controlled through a single resistor without affecting the resonance frequencies. Both circuits have low sensitivities and no passive element‐matching conditions. The introduced VM MISO universal filter has a low output impedance. Moreover, to extract the output currents of the proposed CM SIMO from high impedance terminals, second‐generation current conveyor‐based version of the circuit is introduced. Simulations are made through the PSPICE program, where 0.13‐μm IBM CMOS technology parameters are utilized. DC supply voltages are selected as ±0.9 V. In the experiments, AD844s are used, and DC supply voltages are chosen as ±7.5 V.

A Wide-Band Magnetoelectric Sensor Based on a Negative-Feedback Compensated Readout Circuit.

Magnetoelectric (ME) sensors cannot effectively detect broadband magnetic field signals due to their narrow bandwidth, and existing readout circuits are unable to vary the bandwidth of the sensors. To expand the bandwidth, this paper introduces a negative-feedback readout circuit, fabricated by introducing a negative-feedback compensation circuit based on the direct readout circuit of the ME sensor. The negative-feedback compensation circuit contains a current amplifier, a feedback resistor, and a feedback coil. For this purpose, a Metglas/PVDF/Metglas ME sensor was prepared. Experimental measurements show that there is a six-fold difference between the maximum and minimum values of the ME voltage coefficients in the 6-39 kHz frequency band for the ME sensor without the negative-feedback compensation circuit when the sensor operates at the optimal bias magnetic field. However, the ME voltage coefficient in this band remains stable, at 900 V/T, after the charge amplification of the direct-reading circuit and the negative-feedback circuit. In addition, experimental results show that this negative-feedback readout circuit does not increase the equivalent magnetic noise of the sensor, with a noise level of 240 pT/√Hz in the frequency band lower than 25 kHz, 63 pT/√Hz around the resonance frequency of 30 kHz, and 620 pT/√Hz at 39 kHz. This paper proposes a negative-feedback readout circuit based on the direct readout circuit, which greatly increases the bandwidth of ME sensors and promotes the widespread application of ME sensors in the fields of broadband weak magnetic signal detection and DBS electrode positioning.

Lowering the energy threshold using a plastic scintillator and radiation-damaged SiPMs

The radiation damage to a silicon photomultiplier (SiPM) set on a satellite orbit increases energy threshold for scintillator detectors. We confirmed that 1 krad of radiation increases the energy threshold by approximately a factor of 10, which is worst for our system. Using one or two SiPMs damaged by proton irradiation and a plastic scintillator, we performed the following three experiments in our attempt to lower the energy threshold of radiation-damaged SiPMs to the greatest extent: (1) measurements using a current waveform amplifier rather than a charge-sensitive amplifier, (2) coincidence measurements with two radiation-damaged SiPMs attached to one scintillator and summing up their signals, and (3) measurements at a low temperature. Our findings confirmed that the use of a current waveform amplifier, as opposed to a charge-sensitive amplifier and a shaping amplifier, could lower the energy threshold to approximately 65% (from 198 keV to 128 keV). Furthermore, if we set the coincidence width appropriately and sum up the signals of the two SiPMs in the coincidence measurement, the energy threshold could be lowered to approximately 70% (from 132 keV to 93 keV) with little loss of the acquired signal, compared to that of use of only one scintillator. Finally, if we perform our measurements at a temperature of −20 °C, we could lower the energy threshold to approximately 34% (from 128 keV to 43 keV) compared to that of at 20 °C. Accordingly, we conclude that the energy threshold can be lowered to approximately 15% by using a combination of these three methods.

Monitoring Lubrication and Wear in-situ by triboelectrification Under Vacuum Conditions

Maintaining the condition of the friction pair is an important measure to reduce mechanical failure. This paper integrates a vacuum elastohydrodynamic oil film measurement device and a current amplifier to simultaneously observe the optical interference image, friction coefficient and triboelectric signal during the friction process. In a high vacuum environment, the discharge phenomenon of steel balls corresponds to the time when the friction pair wears. Changes in the friction state in high vacuum environments have a significant impact on triboelectricity. Based on the relationship between the two, a sensor for real-time monitoring of the friction and wear status of the friction pair is designed, which provides a reliable real-time monitoring method for friction pair monitoring in vacuum machinery.