Circuit Devices Research Articles

Accurate time-domain and frequency-domain co-simulation approach for OEICs design with Verilog-A.

Optoelectronic integrated circuits (OEICs) have enhanced integration and communication capabilities in various applications. With the continued increase in complexity and scale, the need for an accurate and efficient simulation environment compatible with photonics and electronics becomes paramount. This paper introduces a method using the Verilog-A hardware language in the electronic design automation (EDA) platform to create equivalent circuit and compact models for photonic devices, considering their dispersion, polarization, multimode, and bidirectional transmission characteristics. These models can be co-simulated alongside electrical components in the electronic simulator, covering both the time and frequency domains simultaneously. Model parameters can be modified at any stage of the design process. Using the full link of an optoelectronic transceiver as an example, analyses from our Verilog-A model system show a mean absolute percentage error of 1.55% in the time-domain and 0.0318% in the frequency-domain when compared to the commercial co-simulation system (e.g., Virtuoso-INTERCONNECT). This underscores the accuracy and efficiency of our approach in OEICs design. By adopting this method, designers are enabled to conduct both electrical-specific and photonic-specific circuit analyses, as well as perform optoelectronic co-simulation within a unified platform seamlessly.

РАЗРАБОТКА И ОПТИМИЗАЦИЯ ЭНЕРГОСБЕРЕГАЮЩИХ СХЕМ ДЛЯ ПОРТАТИВНЫХ ЭЛЕКТРОННЫХ УСТРОЙСТВ

The article discusses modern approaches to the development and optimization of energy-saving circuits for portable electronic devices. The main focus is on reducing energy consumption by using low-power modes of component operation, optimizing the power supply circuit and implementing energy management algorithms at the system level. An analysis of the effectiveness of the proposed solutions is provided using specific devices as an example, with an assessment of their impact on performance and battery life. The results show a significant reduction in power consumption without compromising performance, which confirms the promise of the proposed approaches.

Versatile, in-line optical oxygen tension sensors for continuous monitoring during ex vivo kidney perfusion.

Integration of physiological sensing modalities within tissue and organ perfusion systems is becoming a steadily expanding field of research, aimed at achieving technological breakthrough innovations that will expand the sites and clinical settings at which such systems can be used. This is becoming possible in part due to the advancement of user-friendly optical sensors in recent years, which rely both on synthetic, luminescent sensor molecules and inexpensive, low-power electronic components for device engineering. In this article we report a novel approach towards enabling automated, continuous monitoring of oxygenation during ex vivo organ perfusion, by combining versatile flow cell components and low-power, programmable electronic readout devices. The sensing element comprises a 3D printed, miniature flow cell with tubing connectors and an affixed oxygen-sensing thin film material containing in-house developed, brightly-emitting metalloporphyrin phosphor molecules embedded within a polymer matrix. Proof-of-concept validation of this technology is demonstrated through integration within the tubing circuit of a transportable medical device for hypothermic oxygenated machine perfusion of extracted kidneys as a model for organs to be preserved as transplants.

A Wireless Multimodal Physiological Monitoring ASIC for Animal Health Monitoring Injectable Devices.

Utilizing injectable devices for monitoring animal health offers several advantages over traditional wearable devices, including improved signal-to-noise ratio (SNR) and enhanced immunity to motion artifacts. We present a wireless application-specific integrated circuit (ASIC) for injectable devices. The ASIC has multiple physiological sensing modalities including body temperature monitoring, electrocardiography (ECG), and photoplethysmography (PPG). The ASIC fabricated using the CMOS 180 nm process is sized to fit into an injectable microchip implant. The ASIC features a low-power design, drawing an average DC power of 155.3 µW, enabling the ASIC to be wirelessly powered through an inductive link. To capture the ECG signal, we designed the ECG analog frontend (AFE) with 0.3 Hz low cut-off frequency and 45-79 dB adjustable midband gain. To measure PPG, we employ an energy-efficient and safe switched-capacitor-based (SC) light emitting diode (LED) driver to illuminate an LED with milliampere-level current pulses. A SC integrator-based AFE converts the current of photodiode with a programmable transimpedance gain. A resistor-based Wheatstone Bridge (WhB) temperature sensor followed by an instrumentation amplifier (IA) provides 27-47 °C sensing range with 0.02 °C inaccuracy. Recorded physiological signals are sequentially sampled and quantized by a 10-bit analog-to-digital converter (ADC) with the successive approximation register (SAR) architecture. The SAR ADC features an energy-efficient switching scheme and achieves a 57.5 dB signal-to-noise-and-distortion ratio (SNDR) within 1 kHz bandwidth. Then, a back data telemetry transmits the baseband data via a backscatter scheme with intermediate-frequency assistance. The ASIC's overall functionality and performance has been evaluated through an invivo experiment.

Acid-base equilibrium in non-aqueous medium: colorimetric visualization, estimation of acidity constants and construction of molecular logic gates.

A reversible acid-base probe, (N1E, N4E)-N1, N4-bis((Z)-3-(4-(dimethylamino)phenyl)allylidene)benzene-1,4-diamine (MM1), is introduced for the colorimetric visualization of acid-base equilibria in non-aqueous media. MM1 displays reversible acidochromic behavior, showing exciting colorimetric change varying from weak to strong acid. Also, we have fabricated a colorimetric paper strip-based test kit to visualize acid-base equilibria. A dipstick experiment has been demonstrated to visualize the acid-base equilibria in the gaseous state. This acid-base probe has also been employed to estimate the pKa values of several acidic compounds in a non-aqueous medium using overlapping indicator methods. Based on reversible acidochromic UV-visible absorption spectral and colorimetric behavior, we have constructed a reconfigurable dual input and dual output combinational logic circuit and set-reset memorized device employing acid and base as chemically encoded inputs and corresponding optical outputs. The current report evokes a new protocol for developing various reversible acidochromic probes and its implication for constructing opto-chemical molecular logic gates and estimating the acid dissociation constants of various acidic compounds in non-aqueous media.

Implementation of Bayesian networks and Bayesian inference using a Cu0.1Te0.9/HfO2/Pt threshold switching memristor.

Bayesian networks and Bayesian inference, which forecast uncertain causal relationships within a stochastic framework, are used in various artificial intelligence applications. However, implementing hardware circuits for the Bayesian inference has shortcomings regarding device performance and circuit complexity. This work proposed a Bayesian network and inference circuit using a Cu0.1Te0.9/HfO2/Pt volatile memristor, a probabilistic bit neuron that can control the probability of being 'true' or 'false.' Nodal probabilities within the network are feasibly sampled with low errors, even with the device's cycle-to-cycle variations. Furthermore, Bayesian inference of all conditional probabilities within the network is implemented with low power (<186 nW) and energy consumption (441.4 fJ), and a normalized mean squared error of ∼7.5 × 10-4 through division feedback logic with a variational learning rate to suppress the inherent variation of the memristor. The suggested memristor-based Bayesian network shows the potential to replace the conventional complementary metal oxide semiconductor-based Bayesian estimation method with power efficiency using a stochastic computing method.

Machine Learning-Assisted Device Circuit Co-Optimization: A Case Study on Inverter

Machine Learning-Assisted Device Circuit Co-Optimization: A Case Study on Inverter

Low Power Volatile and Nonvolatile Memristive Devices from 1D MoO2-MoS2 Core-Shell Heterostructures for Future Bio-Inspired Computing.

Memristors-based integrated circuits for emerging bio-inspired computing paradigms require an integrated approach utilizing both volatile and nonvolatile memristive devices. Here, an innovative architecture comprising of 1D CVD-grown core-shell heterostructures (CSHSs) of MoO2-MoS2 is employed as memristors manifesting both volatile switching (with high selectivity of 107 and steep slope of 0.6mVdecade-1) and nonvolatile switching phenomena (with Ion/Ioff ≈103 and switching speed of 60ns). In these CSHSs, the metallic core MoO2 with high current carrying capacity provides a conformal and immaculate interface with semiconducting MoS2 shells and therefore it acts as a bottom electrode for the memristors. The power consumption in volatile devices is as low as 50pW per set transition and 0.1fW in standby mode. Voltage-driven current spikes are observed for volatile devices while with nonvolatile memristors, key features of a biological synapse such as short/long-term plasticity and paired pulse facilitation are emulated suggesting their potential for the development of neuromorphic circuits. These CSHSs offer an unprecedented solution for the interfacial issues between metallic electrodes and the layered materials-based switching element with the prospects of developing smaller footprint memristive devices for future integrated circuits.

Power Quality and Break-Even Points in the Use of Electric Motorcycles in the Case of the Thailand Residential Building

The use of electric motorcycles (EMCs) is rapidly increasing because EMCs are comparable in price to internal combustion engine motorcycles (ICE motorcycles), can be charged at home, and do not cause pollution. However, using EMCs in residential electrical systems is still a new issue in Thailand, as the Thai power grid was not originally designed to support electric vehicle charging. Therefore, the effect that may occur on the electrical system of a house should be studied. In this study, the power quality when charging an EMC in a residential electrical system is investigated by considering the circuits of various electrical devices according to their actual consumption behavior. Three electric motorcycles with battery capacities of 20, 30, and 40 Ah were used to investigate the effects of charging these motorcycles through the electrical system of a house. The experiment was conducted in a laboratory that replicated the electrical system of a house, and the conditions and patterns of power consumption were identical in all three cases. The test results were considered in terms of power quality, voltage harmonics, and current power system harmonics to analyze the effects on the electrical system in each circuit and to compare the charging differences of each motorcycle model. Next, it was determined that using an EMC is more cost-effective than using an ICE motorcycle. ICE motorcycles will eventually be completely replaced by EMCs, and our research will enable informed decision-making for electric motorcycle riders, researchers, and automotive corporations.

(Invited) Fundamentals of Thin Film Growth and Etching: How Small Atomic Processes Govern Macroscopic Effects

In order not to have our children inherit a huge problem in the future, we quickly have to realize the energy transition to renewable sources, which requires also energy storage devices and, thus, Li ion batteries. Although significant progress has been made during recent years regarding battery capacitance, cycle life time, deterioration, and fast charging capabilities, any further improvement becomes increasingly more difficult.The reason for this is manifested in the top-down approach, which quickly delivers results, and thus products, by screening the parameter space and evaluating available options. At this point, however, further improvements often require a deep, fundamental understanding of all processes, and a change to a bottom-up approach is highly recommended, if not even essential.Using Scanning Tunneling Microscopy movies, I will show in my talk how a small change in adatom formation energy and adatom diffusion barrier leads to a huge morphology change of the growing film. After providing the insights to the well-known homoepitaxial growth modes, I will introduce one specific atomic barrier that leads to an instability and triggers 3D growth. The 2D analogous of this barrier at a step edge, leads to dendritic island shapes, and the combination of both, the 2D and 3D instability, leads to dendrites as observed also in the batteries. With this in mind, I will show the dualism between adatoms and vacancies, which naturally explains also the equivalent, inverse growth modes during etching or dissolution including their instabilities.From here we will switch gears and focus on polycrystalline film aspects, and, thus, the grain boundary network. I will show, again on the atomic scale, how the grain boundary energy determines the surface structure from extremely rough to flat and smooth. Quite surprisingly, I will further demonstrate how a tiny variation in the dilute adatom/vacancy equilibrium-pressure on the surface, during growth or dissolution, can setup pressures variations in the grain boundary network that exceed the pressure of the deepest point of all our world seas: the Mariana Trench.These enormous compressive (and tensile) stresses are to a large extent reversible. However, due to the differences in diffusion constants in combination with the huge reservoir of grain boundary volume in the film, complications arise on the atomic scale at the triple point/lines, where the grain boundaries penetrate the surface. Mass accumulation or depletion leads to hillocks and grooves. Moreover, the remaining accumulated intrinsic film stress can also trigger whisker growth, which, on the basis of the involved atomic processes, clearly has to be distinguished from dendritic growth.Although fundamentally still not understood, whisker growth leads to many failures, like short circuits in electronic devices and batteries. Their penetrating forces can be enormous, pushing through even hard oxide layers and films (and the SEI).As many of the described effects play a major and critical role in Li ion batteries, and while I realize that I am adding seemingly hopeless, additional complexity, I will finally provide some basic strategies and concepts that we learned on how to tune and influence the previously mentioned effects efficiently on the atomic scale by using additives.

Enhancing Thermal Conductivity, Electrical Insulation, and Mechanical Strength of Polydimethylsiloxane Composites with Sandwich Structure

In this article, boron nitride (BN)/carbon nanotube (CNT)/boron nitride (BN) (BCB) film of sandwich structure is prepared by vacuum‐assisted filtration. Compared with the thermal conductivity (λ) of BNs–cellulose nanocrystals (CNCs) (BC) film, the λ of sandwich structured BCB films with the same thickness (The preparation process consists of one layer of BC and one layer of CNTs–CNCs (CC) until the completion of three layers of filtration) has been significantly improved. Then, the polydimethylsiloxane (PDMS) matrix is infiltrated into the BCB films by the ultrasonic‐assisted forced infiltration method. Prepared BN/CNT/BN/PDMS (BCBP) composites with sandwich structure have excellent λ and mechanical performance. When the weight ratio of BNs to CNCs is 20:1, the λ of BCBP20:1 attains 5.253 W (m K)−1, compared with other thermally conductive composites with the same thickness (0.1 mm), it has an obvious increase. Besides, the dielectric properties and mechanical flexibility of BCBP are also systematically analyzed. This sandwich structure is prepared in such a method that the BCBP will not cause short circuits in electronic devices under high temperatures while having high λ.

Design of a high bandwidth ECG signal low noise amplifier circuit for wearable devices

Nowadays, more than one million people die due to heart problems annually. Detecting the Electrocardiogram curve is an effective way to evaluate heart condition. Compared with large devices in the hospital, wearable devices are showing their advantage in detecting peoples Electrocardiogram whenever and wherever possible. However, in traditional amplifier circuit design, there is less attention to the bandwidth. The noise is negatively correlated with the current while the power consumption is positively correlated with the current, so it is challenging to balance the noise and power. Therefore, a design of a high bandwidth Electrocardiogram signal low noise amplifier circuit for wearable devices is proposed in this paper. The improved circuit is based on a conventional instrumentation amplifier and consists of two stages. The op-amps were replaced with Operational Transconductance Amplifier. The circuit also has a Driven-Right-Leg circuit part, which can tremendously reduce the effect of common-mode noise. The simulation result shows that the circuit has a high bandwidth and stable gain. Meanwhile, the circuit consumes less power and has a low integrated input-referred noise. This study is extremely helpful in expanding the application of wearable Electrocardiogram signal-detecting devices.

Approach to Computer Modelling of Power Energy Devices’ Periodic Modes

The increasing complexity of power energy devices poses new challenges for designers, and the solutions depend on the efficiency and adequacy of computer modeling of electromagnetic processes in real circuits of power energy devices with the required accuracy. Using known methods for constructing equivalent circuits, it is possible to obtain equivalent circuits of power energy devices. However, a high number of nodes of equivalent circuits (hence, a high order of systems of differential equations) often does not provide solving the analysis problems with the required accuracy and with time constraints which requires new, more effective approaches for modeling periodic modes of power energy devices’ circuits.

Принцип преобразования сигналов в фотонных телекоммуникационных устройствах с использованием объёмных Фурье-голограмм

The relevance of the transition to a new element base for the construction of tele-communication systems and devices with improved technical characteristics based on photonics technologies, including holographic photonics, is shown. To improve the technical characteristics and expand the functionality of the equipment of telecommunication systems in the construction of their structures, it is proposed to use volumetric Fourier holograms. The principle of converting the information parameters of electrical signals in a photonic telecommunication de-vice with a volumetric Fourier hologram into the corresponding parameters of a holographic interferogram is formulated and a block diagram of this principle is developed. It is indicated that for the practical use of the principle of electro-optical signal conversion in photonic telecommunication devices with optical modulators and volumetric Fourier holograms in their design, each stage of the implementation of this principle must be considered as a separate task. The functional purpose of individual elements of the structural scheme of the transformation principle is described. Possible methods of modulation of the parameters of the luminous flux in a photonic telecommunication device with a volumetric Fourier hologram are shown. Variants of structural schemes of holographic pho-tonic devices with reflective and reflective-transmitting Fourier holograms, re-spectively, are presented. Mathematical relations are given that determine the nature of the distribution of the intensity of the light flux on the interferogram formed in the plane of the volumetric Fourier hologram. The influence of a volumetric Fourier hologram on the parameters of a coherent light flux is considered. It is noted that a holographic interferogram formed in the plane of a volumetric Fourier hologram is projected into the searchlight zone while maintaining the amplitude-phase relations between interfering light streams, but with a change in the scale of the projected interferogram. Recommendations on the use of the principle of signal conversion in photonic telecommunication devices using volumetric Fourier holograms have been developed. The influence of electro-optical and acousto-optical modulators of a coherent light flux with a spherical wavefront on the position of its phase center is explained. It is indicated that the sensitivity of the parameters of the holographic interferogram to changes in the voltage of the modulating electrical signal can be adjusted by changing the parameters of the elements of the optical circuit of the holographic photonic telecommunication de-vice and the recording conditions of the volumetric Fourier hologram. A reasonable conclusion is made about the feasibility of constructing photonic telecommunication devices using optical light flux modulators in combination with volumetric Fourier holograms.

Improving efficiency of silicon solar cells by integrating SiO2-coated lead-free Cs3Bi2Br9 perovskites quantum dots as luminescence down-shifting layer

Lead-based perovskite quantum dots (QDs) have promising applications in optoelectronic devices, but commercial applications are limited by the potential toxicity and poor stability of lead. Meanwhile, there are lattice, polarity, and thermal expansion coefficient mismatches in integrating semiconductor materials onto the surface of photoelectronic circuit devices, resulting in high-density defects limiting the reliability of photoelectronic devices. Therefore, there is a need to investigate perovskite alternatives that are non-toxic, stable, and can be effectively coupled to silicon photonic circuits. In this paper, lead-free perovskite Cs3Bi2Br9/SiO2 QDs were synthesized. The emission wavelength falls within the 400–560 nm range, exhibiting vibrant blue photoluminescence and demonstrating exceptional air stability for a duration exceeding 60 days. Optical tests and density-functional theory (DFT) calculations show that the silica shell layer effectively binds the electron and hole wave functions, prevents photon-generated carriers from escaping, reduces surface defects, and improves the carrier recombination probability. Meanwhile, using Cs3Bi2Br9/SiO2 QDs as a luminescent down-shifting (LDS) layer in combination with a conventional silicon solar cell, the photovoltaic conversion power was increased by 1.82%. Hence, the core-shell structure is designed by the green environmental protection method to control the improvement of the PL characteristics of QDs, which opens a window for the synthesis of new barrier materials in ethanol and water systems, making the Cs3Bi2Br9/SiO2 QDs have great potential for the application of novel optoelectronic devices in the future.

Design of ECG circuits for wearable devices

Heart diseases have become more and more prominent in recent years. ECG signals can accurately reflect the health of hearts during the detection process. The use of wearable ECG devices requires low power consumption, a high common-mode rejection ratio, and minimal noise. Traditional research has concentrated on lowering the circuit's overall power dissipation, which typically results in less current flowing through the amplifier but higher circuit noise. Therefore, this places higher demands on the amplifier in the circuit. Electronic devices are becoming smaller due to the rapid development of semiconductor technology. Amplifiers designed for semiconductor devices can effectively solve the problems mentioned above. The circuit created in this study has a low power need, a high common-mode rejection ratio, is compact, has a high input impedance, and has a low input-referred noise level. In addition, LT-Spice software was used to design and simulate the circuit, and the results were analyzed and calculated accordingly. The circuit meets the requirements of the project design. The frequency range of the circuit is 1mHz - 227.9Hz. The differential gain of the circuit is 36.6dB. The integrated input-fred noise is 3.94uV. The total consumption of electricity is 4.67W. These data indicate that the circuit has a high gain in the frequency range of ECG signals, which can filter out other interference signals. It also solves the problems of power consumption and noise.

A hybrid process for integration of organic electrochemical transistors for high uniformity & reliability

Photolithography is believed to be a complementary technique to large-area printing, allowing for nanometer-scale integration and offering cost-efficiency. For organic electronics though, adapting photolithography is very challenging due to chemical incompatibilities. However, with the help of Alexander Zakhidov, orthogonal resins opened up the prospect of adapting the well-established process of photolithography for organic electronics. Here, we present a hybrid fabrication method for organic electrochemical transistors by combining orthogonal photolithography and inkjet printing, enabling high uniformity and reliability. We demonstrate how the resolution of each process affects the uniformity, and we explore the advantages of this process for device scaling and circuit integration.Graphical abstract

Analysis of Novel Energy-Efficient Converters to Ensure the Required Quality of Electrical Energy

This article proposes several solutions for the use of novel AC voltage regulators as electrical energy quality conditioners and for the use of a half-bridge voltage inverter circuit as an active filter. This study was carried out with a real object, and more attention was paid to it. Structural models of electrical energy quality assurance systems, the calculation of control system elements and experimental results are presented. In particular, the use of a half-bridge voltage inverter circuit was considered as a replacement for the passive filter of the battery charger and rectifier device. AC voltage regulators are also used as compensators for higher-current harmonics, namely active filters and reactive power, voltage drop, voltage unbalance and flicker effect compensators. Block diagrams of power quality conditioners are presented, control algorithms are developed and the results of the current high-frequency harmonics compensation, reactive power and signal balancing are presented. The results of an active filter experiment based on the NRT 160.220 charge-rectifier device circuit showed a reduction in ripple of up to 1% with smaller dimensions compared to a passive filter. The control characteristics and external characteristics of the regulators are removed. The dependences of the current THD factor and the power factor are presented depending on the modulation depth for AC voltage regulator circuits used as power quality conditioners.

Design and implementation of isolated multilevel inverter with lower number of circuit devices

AbstractGalvanic isolation is an integral part for the grid connected solar PV system. With the advancement of multilevel inverters for the grid‐connected application, the multilevel inverters having isolation are not sufficiently discussed in the literature. Here, a 15‐level isolated multilevel inverter topology requiring only 13 switches is proposed. The proposed single‐phase isolated converter requires reduced switches to generate 15‐level ac output voltage with voltage gain of 7. Comparatively, the switches connected in the proposed converter undergo less voltage stress as compared to the MLIs reported in the literature. A comparison of the proposed converter structure to the state‐of‐the art MLIs described in the literature is included. The experimental results captured on a low‐power laboratory prototype are used to validate the performance of the proposed converter. The claimed efficiency of the converter calculated using simulation results is found to be 97.1%. However, the efficiency calculated using experimental results is 95.2% at 700 W.

Accelerated degradation data analysis based on inverse Gaussian process with unit heterogeneity

The unit heterogeneity of products and the nonlinear parameter-stress relationship often exist in practice. Therefore, considering the unit heterogeneity, the nonlinear accelerated model and inverse Gaussian process are developed to depict the accelerated degradation data. On the other hand, this more realistic model leads a challenge to derive the model parameter interval estimation. Thereby, a novel two-step interval estimation method is proposed for the proposed accelerated degradation model. First, generalized confidence intervals of the parameters characterizing random effect are derived from the Cornish–Fisher expansion, and their cumulative distribution functions are obtained. Then, using the generalized pivotal quantity procedure, generalized confidence intervals of the accelerated model parameters are derived. In addition, generalized confidence intervals of predictive reliability indexes are derived to guide the practical application. Finally, simulation studies and two real examples on Spiral springs and integrated circuit devices are presented to demonstrate the implementation of the proposed method.