Interface Circuit Research Articles

Arterial Distension Monitoring Scheme Using FPGA-Based Inference Machine in Ultrasound Scanner Circuit System.

This paper presents an arterial distension monitoring scheme using a field-programmable gate array (FPGA)-based inference machine in an ultrasound scanner circuit system. An arterial distension monitoring requires a precise positioning of an ultrasound probe on an artery as a prerequisite. The proposed arterial distension monitoring scheme is based on a finite state machine that incorporates sequential support vector machines (SVMs) to assist in both coarse and fine adjustments of probe position. The SVMs sequentially perform recognitions of ultrasonic A-mode echo pattern for a human carotid artery. By employing sequential SVMs in combination with convolution and average pooling, the number of features for the inference machine is significantly reduced, resulting in less utilization of hardware resources in FPGA. The proposed arterial distension monitoring scheme was implemented in an FPGA (Artix7) with a resource utilization percentage less than 9.3%. To demonstrate the proposed scheme, we implemented a customized ultrasound scanner consisting of a single-element transducer, an FPGA, and analog interface circuits with discrete chips. In measurements, we set virtual coordinates on a human neck for 9 human subjects. The achieved accuracy of probe positioning inference is 88%, and the Pearson coefficient (r) of arterial distension estimation is 0.838.

A chaos game optimization algorithm-based optimal control strategy for performance enhancement of offshore wind farms

This paper presents a novel application of the chaos game optimization (CGO) algorithm to optimally design PI controllers for power electronic interface circuits of offshore wind farms (OWF) consisting of a permanent magnet synchronous generator powered by a variable-speed wind turbine. The OWF is linked to the network via a high-voltage direct current (HVDC) transmission system. The CGO metaheuristic method is employed to fine-tune voltage source converter (VSC)-based HVDC transmission systems’ proportional-integral controller gains. The study explores multiple strategies to extract the highest power from the system while ensuring stability under symmetrical and unsymmetrical fault conditions. The CGO algorithm consistently yields superior results to other algorithms, improving system regaining and stability post disturbances. Consequently, the technique enhances the dynamic and transient stability of the OWF. The detailed study is implemented using MATLAB/Simulink.

Top-Down Design Method of a Time Domain Accelerometer with Adjustable Resolution.

A top-down design methodology and implementation of a time domain sensor is presented in this paper. The acceleration resolution of the time domain sensor is equal to the time-measurement accuracy divided by the sensor sensitivity. Combined with the sensitivity formula, the acceleration resolution is proportional to the vibration amplitude, the time-measurement accuracy, and the third power of the resonant frequency. According to the available time-measurement accuracy and the desired acceleration resolution, the parameters including the vibration amplitude and the resonant frequency were theoretically calculated. The geometrical configuration of the time domain sensor device was designed based on the calculated parameters. Then, the designed device was fabricated based on a standard silicon-on-insulator process and a matched interface circuit was developed for the fabricated device. Experimental results demonstrated that the design methodology is effective and feasible. Moreover, the implemented sensor works well. In addition, the acceleration resolution can be tuned by adjusting the time-measurement accuracy and the vibration amplitude. All the reported results of this work can be expanded to other time domain inertial sensors, e.g., a gyroscope or tilt sensor.

Simulations of superconducting quantum gates by digital flux tuner for qubits

Abstract The interconnection bottleneck caused by limitations of cable number, inner space and cooling power of dilution refrigerators has been an outstanding challenge for building scalable superconducting quantum computers with the increasing number of qubits in quantum processors. To surmount such an obstacle, it is desirable to integrate qubits with quantum–classical interface (QCI) circuits based on rapid single flux quantum (RSFQ) circuits. In this work, a digital flux tuner for qubits (DFTQ) is proposed for manipulating flux of qubits as a crucial part of the interface circuit. A schematic diagram of the DFTQ is presented, consisting of a coarse tuning unit and a fine-tuning unit for providing magnetic flux with different precision to qubits. The method of using DFTQ to provide flux for gate operations is discussed from the optimization of circuit design and input signal. To verify the effectiveness of the method, simulations of a single DFTQ and quantum gates including a Z gate and an iSWAP gate with DFTQs are performed for flux-tunable transmons. The quantum process tomography corresponding to the two gates is also carried out to analyze the sources of gate error. The results of tomography show that the gate fidelities independent of the initial states of the Z gate and the iSWAP gate are 99.935% and 99.676%, respectively. With DFTQs inside, the QCI would be a powerful tool for building large-scale quantum computers.

Fabrication and Implementation of PVA Thin Film-based Relative Humidity Sensor

This paper presents the fabrication of polyvinyl alcohol (PVA)-based relative humidity sensors using copper interdigitated electrodes (IDEs). These sensors were fabricated by patterning copper IDEs onto FR4 fiberglass substrates and coating them with a thin film of PVA. By varying the number of IDE electrode pairs and the concentration of PVA, the sensors exhibited different resistance values, demonstrating an inverse relationship with the number of IDE electrodes and PVA concentration. Additionally, the thickness of the sensing layer, controlled by spin coating speed, affected the resistance of the sensors. The fabricated sensors achieved a humidity measurement range from 50% to 99% RH based on resistance changes. Furthermore, an interface circuit was designed to integrate the fabricated sensors with an ESP8266 microcontroller, achieving accurate measurements above 74% RH.

Literature Review, Analysis of the Performance of Operational Amplifier Applied in Controlling Systems: Summary, Analysis, and Overview

As part of modern electronic technology, the operational amplifier is widely used in signal conditioning, sensor interface circuits, controller design, and actuator drives of automatic control systems. Improvement: In accurate controlling systems, factors such as linearity, noise performance, and stability directly influence the accuracy and speed of response of the whole system. Thus, it is vitally important for Improving the overall performance of automated control systems to learn and improve the performance of the operational amplifier. With the development of Industry 4.0 and intelligent manufacturing, modern controlling strategies such as adaptive control and intelligent controlling demand much more from the operational amplifier.

NbN-based half-flux-quantum element for integration with superconducting qubits

Half-flux-quantum (HFQ) logic is a superconductor logic family comprising conventional Josephson junctions (0-JJs) and π Josephson junctions (π-JJs). The energy scale of HFQ logic can be flexibly reduced by phase shifts owing to π-JJs; thus, HFQ circuits are a promising building block for qubit interface circuits. In this study, we demonstrate an NbN-based HFQ circuit element compatible with NbN-based superconducting qubits for all-NbN monolithic integration of qubits and HFQ circuits. The use of NbN is beneficial for both qubits and HFQ circuits owing to its high-quality junctions and high kinetic inductance. First, we developed a prototype of an NbN-based 0-JJ/π-JJ hybrid fabrication process for designing HFQ circuits. We evaluated 0-JJs and π-JJs fabricated through the hybrid process, which demonstrated that the 0-JJs had a small deviation with regard to critical current density and the π-JJs had a sufficiently high critical current density to work as π phase shifters. Furthermore, we fabricated an HFQ superconducting quantum interference device, which is one of the most fundamental elements in HFQ circuits, and observed clear HFQ-period modulation in the magnetic flux dependence of the maximum current at 4.2 K.

Biomechanical MEMS Electrostatic Energy Harvester for Pacemaker Application: A Study of Optimal Interface Circuit.

The leadless pacemaker is the most recent pacemaker concept, developed to overcome conventional pacemakers' limitations. This technology offers better comfort to the patients, lower risk from implantation, and higher reliability. However, these devices suffer from limited battery lifetime due to the extreme miniaturization required for implantation inside the heart cavities. This work proposes extending the battery lifetime by converting biomechanical heartbeat energy into electricity using an innovative electrostatic MEMS energy harvesting device. Based on theoretical models and experiments, we propose a general approach to choosing the optimal interface circuit which considers the parasitic capacitance of the circuit, as it is an imperfection that significantly affects the power performance. According to the energy consumed by the last generation commercial leadless pacemakers, the proposed MEMS solution with optimal interface circuit experimentally showed the possibility of extending the pacemaker battery lifetime by up to 44%.

Next generation mobile edge computing wireless sensor network based Japanese remote interactive practical teaching platform

To solve the problem of lack of practice in Japanese teaching, a design of a Japanese remote interactive practical teaching platform based on the modern edge computing-based wireless sensor network is proposed. In terms of hardware, it mainly refits interactive mobile edge computing, wireless sensor networks, microprocessors, and other equipment, and adjusts the interface circuit. The Japanese teaching data and relevant Japanese teaching resources generated in the process of Japanese Teaching of practical courses are stored in the corresponding database table according to a certain format, and the logical relationship between database tables is used to update the database. The software function of the platform is designed with the support of a database and hardware equipment. It consists of multiple modules, including platform user roles, interactive practical teaching and management, practical resource management and distribution, practice project information release, practice investigation statistics, and platform operation safety. Through the above design, the operation of a Japanese remote interactive practical teaching platform is realized. The test results show that there is no significant difference in the function realization of the design platform, but when multiple users are online at the same time, the interaction performance of the design platform is stronger, that is, the operation performance of the platform has obvious advantages.

MEMS Pressure Sensors Design, Simulation, Manufacturing, Interface Circuits: A Review

MEMS Pressure Sensors Design, Simulation, Manufacturing, Interface Circuits: A Review

An accelerated modelling method of full-bridge modular multilevel converter considering dead-time

To avoid short-circuits of the same side switching of power converters, the dead time is of significance in the pulse trigger gating signal for full bridge modular multilevel converter (FB-MMC). However, the previous equivalent models use the binary resistance switching model to equivalent the switching state which is impossible to simulate the switching with dead time, and the detailed model (DM) with higher levels is time-consuming and inefficient in electromagnetic transient (EMT) simulation. To address this problem, based on the state-space averaging method, a speed-up average value model (AVM) of FB-MMC considering dead time is proposed. Firstly, the working state of FB-MMC is obtained through analysing the switching states with dead time and is classified into three cases according to the capacitor. Secondly, derived from state-space equation, the three cases are integrated into a unified model by introducing the duty cycle, and then the equivalent controlled source is used as the interface circuit between the external grid and capacitor. Finally, a 49-level two-terminal MMC-HVDC system consisting of FB-MMC is constructed in PSCAD / EMTDC simulations, showing that the proposed AVM compared with DM has high accuracy and operation efficiency.

A Novel Rectifier-Less Synchronous Electric Charge Extraction and Inversion Interface Circuit for PE Energy Harvesters

A Novel Rectifier-Less Synchronous Electric Charge Extraction and Inversion Interface Circuit for PE Energy Harvesters

A high-efficiency optimized bias-flip energy harvesting system for IoT applications

This paper presents a high-efficiency optimized bias-flip energy harvesting system for Internet of Things (IoT) applications. The harvester consists of a piezoelectric transducer and an interface circuit. Unlike previous bias-flip harvesters, a piezoelectric transducer uses an optimized electrode structure instead of a monolithic electrode to reduce the internal capacitance of the piezoelectric transducer and increase the voltage flip efficiency and maximum output power. The optimized bias-flip harvester does not increase the inductor value or aspect ratio of flip switches to increase efficiency and does save chip area and system volume. While the interface circuit uses a switched-capacitor controller to control the gate-overdrive of the flip switches, employing the adiabatic technique reduces the power consumption of the switching in the control circuit by about 10%. Theoretical analysis of the electrode length effect on the voltage flip efficiency and output power has been performed. Theoretical analysis is confirmed by COMSOL and HSPICE simulations. The maximum output power of the proposed harvester is about 7.4 times the FBR and has superior performance compared to previously reported interface circuits.

Design of Photoelectric Positioning System and Realization of Its Positioning Mathematical Equation

The research of photoelectric positioning system based on wireless data transmission is a multidisciplinary research direction. In the design of photoelectric positioning system, the LED used for light sensing is selected as the light source, and the AC/DC isolated LED driving circuit based on AP3706 is designed. When designing photoelectric conversion circuit, considering the influence of noise interference on detection accuracy, a capacitor is added and connected in parallel with the feedback capacitor. In order to improve the detection accuracy, reduce the relative error of the four-channel signal processing process and maintain the consistency of the four channels, a noninverting amplifier circuit composed of four operational amplifiers LM324 amplifier chips is adopted in this study. NewMsg-RF2401 module is used for wireless data transmission. The system control module adopts ADμC841 single chip microcomputer as the control core. According to the characteristics of this single chip microcomputer, the corresponding ADC module input drive circuit and control-data transmission interface circuit are designed. While designing the hardware of the system, it is necessary to calculate the positioning position. In this study, a positioning mathematical equation is proposed, which can obtain the position of the moving target in the geographical area under the wireless transmission network. In the experiment, firstly, the implementation process of the positioning mathematical equation is described, and then the performance of the proposed positioning mathematical equation is compared with that of the random positioning equation and the binary positioning equation. The results show that more messages can be transmitted by using the positioning mathematical equation proposed in this study. Based on this, it is used in the positioning system designed in this study, which is unfolded under the condition of constant background light, adjusts the position of the movable light source and determines the position coordinates. According to the horizontal and vertical displacement of the light source detected by the system, the positioning error is less than 0.1%, which is in line with the design expectation.

Energy Harvesting from Water Flow by Using Piezoelectric Materials

As a promising energy‐harvesting technique, an increasing number of researchers seek to exploit the piezoelectric effect to power electronic devices by harvesting the energy associated with water flow. In this emerging field, a variety of research themes attract interest for investigation; these include selection of the excitation mechanism, oscillation structure, piezoelectric material, power management interface circuit, and application. Since there has been no comprehensive review to date with respect to the harvesting of water flow using piezoelectric materials, herein relevant work in the last 25 years is reviewed. To ensure that key aspects of the water‐flow energy harvester are overviewed, they are discussed in the context of energy‐flow theory, which includes the three stages of energy extraction, energy conversion, and energy transfer. The development of each energy‐flow process is reviewed in detail and combined with meta‐analysis of the published literature. Correlations between the harvesting processes and their contribution to the overall energy‐harvesting performance are illustrated, and directions for future research are also proposed. In this review, a comprehensive understanding of water‐flow piezoelectric energy harvesting is provided and it is aimed to guide future research and the development of piezoelectric harvesters for water‐flow‐powered devices is promoted.

Velocity-Controlled Piezoelectric Switching Energy Harvesting Device

The main purpose of this paper is to design the interface circuit of the piezoelectric energy harvesting device which can be suitable for a resistive load o a capacitive load. The vibrating velocity is detected to control the active rectifier to make the power factor correction of the piezoelectric layers. However, there are switching losses in the active rectifier in practice. The dead time and an inductor are thus taken into consideration to minimum the switching loss. The proposed circuit can increase 4 times than typical interface circuit of the piezoelectric layer, and can increase the charging speed of the capacitive storage buffer as well.

Single inductor multi-PZTs SECE and electromagnetic voltage multiplier rectifier hybrid interface circuit

This paper proposes a single inductor multi-piezoelectric transducers (PZTs) SECE and electromagnetic voltage multiplier rectifier hybrid interface circuit (MP-SECE-VMR), which harvest energy from multi-input PZTs and electromagnetic generator (EMG). The MP-SECE-VMR adopts a voltage multiplier rectifier circuit, utilizing the diode-connected MOSFET configuration which used as diodes to effectively reduce voltage losses during rectification. Experimental tests confirm that this circuit efficiently extracts energy from PZTs despite differences in their phase relationships. The low input voltage from the EMG is effectively elevated through the voltage multiplier rectifier, enabling simultaneous extraction with the PZTs. The proposed MP-SECE-VMR circuit extracts 1.2 mW of power from two PZTs with open-circuit amplitudes of 9 V and 11 V respectively, as well as from an EMG input with an open-circuit amplitude of 3 V and a frequency of 5 Hz. Furthermore, the proposed circuit effectively enhances output power while expanding the working load range compared to single-source energy extraction.

A Dual-Output Rectifier-based Self-Powered Interface Circuit for Triboelectric Nanogenerators

A Dual-Output Rectifier-based Self-Powered Interface Circuit for Triboelectric Nanogenerators

Active Neural Interface Circuits and Systems for Selective Control of Peripheral Nerves: A Review.

Interfaces with peripheral nerves have been widely developed to enable bioelectronic control of neural activity. Peripheral nerve neuromodulation shows great potential in addressing motor dysfunctions, neurological disorders, and psychiatric conditions. The integration of high-density neural electrodes with stimulation and recording circuits poses a challenge in the design of neural interfaces. Recent advances in active electrode strategies have achieved improved reliability and performance by implementing in-situ control, stimulation, and recording of neural fibers. This paper presents an overview of state-of-the-art neural interface systems that comprise a range of neural electrodes, neurostimulators, and bio-amplifier circuits, with a special focus on interfaces for the peripheral nerves. A discussion on the efficacy of active electrode systems and recommendations for future directions conclude this paper.

Thin-Film Transistor-Based Sensor Interface Circuits Enabling Distributed Local In-Module Solar Cell Temperature Monitoring

Accurate efficiency prediction, improved reliability, and extended lifetime of solar modules are the key driving factors for investment and research in photovoltaic (PV) systems. Enhanced performance and more refined models are realized by incorporating data derived from localized monitoring of solar modules. This work combines interface circuits designed in flexible thin-film transistors (TFTs) with distributed temperature sensors integrated into solar cell lamination enabling in-module within-cell PV monitoring. A TFT multiplexer selects between sensors and is commanded through a serial peripheral interface (SPI) to reduce the IO connections, while the low offset unity-gain TFT buffer enables precise signal transfer. The in-cell sensors together with TFT read-out circuitry demonstrate accurate outdoor temperature monitoring, comparable to silicon integrated circuits.