一种光电探测器接口电路的响应特性分析

针对窄脉冲激光时域/频域特性,对窄脉冲激光电路设计进行了详细的分析,包括探测器光敏面面元尺寸分析,以及取样电阻、反馈电容对信号带宽和信号完整性的影响等。为了提高探测系统的信噪比、稳定性等要素,对两种典型的光电接口电路进行了理论分析和软件仿真,得到不同的探测器结电容、取样电阻、反馈电容等参数对窄脉冲激光探测电路光电接口带宽、输出信号幅值、脉宽等响应特性的影响。根据不同种类的探测器及脉冲激光探测信号的频率特性,选取不同的偏置与放大电路,可以使前置光电接口电路的性能达到最佳。     

基于VC＋＋的LED光电参数测试系统设计

本文针对发光二极管（LED）生产的实际需求,给出了新型LED光电参数测试系统的软硬件设计方案。利用功能强大的AVR单片机,结合高精度数控恒流源技术、光电转换处理技术、USB通信技术以及VC＋＋技术,实现了LED光电参数的在线测试,并提供了与分选设备通信的接口,适用于工业生产流水线上。实践证明,本测试系统实现了快速、准确、可靠的测试,以及测试自动化,提高了工作效率。     

HMR3000电子罗盘与DSP的接口设计及编程

针对光电搜索侦察系统报告搜索到的空中目标当前方位、俯仰位置给后端武器打击系统的需要,在光电搜索系统与后端武器打击系统之间建立大地坐标系是解决此类问题的较好方法,以便后端武器打击系统指向搜索到的空中目标.介绍了数字电子罗盘HMR3000的接口特性,给出了HMR3000的控制编程以及与DSP的接口电路,同时也给出了HMR3000电子罗盘获取光电搜索系统平台方位轴系相对地理正北的获取流程和编程实现方法以及DSP端相关程序.结果表明系统坐标系建立精度达到+-0.5°,重复精度达到+-0.1°,且能稳定运行.     

一种低噪声的光电二极管阵列接口电路的设计

由于光电二极管阵列的暗电流以及后续处理电路的噪声对其信号输出有很大影响,所以设计了一种低噪声的光电二极管阵列接口电路.接口电路将感光二极管阵列和补偿二极管阵列输出的信号经过积分放大处理后再进行差动放大,降低瞬态干扰和暗电流噪声对输出信号的影响.对视频信号和无信号状态分别进行采样和保持,同时触发多次模数转换信号,以利于数据采集和降噪处理.测试结果表明,以上措施有效降低了光电二极管阵列输出信号的噪声.     

应用电路精选

AD42l光电隔离接口DAC:一8420光电隔离接口光电隔离同步压频转换器AD652应用电路应用电路精选     

一种新型光收发模块的研制

报道了一种基于垂直面腔发射激光器(verti-calcavitysurfaceemittinglaser,VCSEL)和光电探测器PIN的混合集成12通道40Gb/s并行光收发模块;介绍了光学封装工艺和光电集成技术。测试结果显示,性能指标符合OIF-VSR5以及ITU-TG.693接口的指标要。     

一种SSI接口光电编码器数据并行采集设计方法

SSI接口即同步串行接口具有传输速度快、连线简单、抗干扰能力强等优点,因而在光电编码器上得到了越来越广泛的应用,但其与计算机接口的连接实现较为复杂,在一定程度上影响了SSI接口光电编码器的推广和应用.基于复杂可编程逻辑器件CPLD开发的SSI接口模块SSI208P,实现了SSI接口编码器数据的高速并行采集.文章对SSI208P模块进行了详细介绍,并给出了硬件设计和软件设计思路及实现方法.     

用于并行数据传输的10Mbit/S小型化光纤计算机接口

我们研制了一种中央处理机(CPU)和外设备之间的光纤传输小型计算机接口。数据字长20bit,传输速率10Mbit/s。光缆由20根突变光纤组成,可长达120米。把光电转换器件(即LED和单片集成光电二极管接收器)装配在配线的有源连接器里并牢固地固定好相应的光纤端子。连接器的插针导通TTL信号。这种光接口比通常的电接口体积小得多。在该计算机系统中,接口和设备之间用多芯导线连接,它们包括多脚连接器,驱动器、接收器集成片以及印刷电路板(PC)。通常五个IC中有一个是接口电路。这些连     

液晶显示空间光调制器及其在光电混合处理中的应用

本文系统地介绍了我们研究改装成功的几种液晶显示空间光调制器,以及它们与计算机的接口,并且给出了它们在实时光电混合处理中的应用。     

某型海上救助直升机加装光电设备适应性设计

从系统的角度论述某型海上救助直升机加装光电设备的适应性设计,通过直升机与光电设备之间的机械、电气接口、安装方式、布线设计、电磁干扰等方面,详细论证了救助直升机的改装过程以及应用。通过实际应用验证,直升机加装光电设备能有效提高海上救助能力、增强海上救助手段,在现代化海上搜救应急保障救援体系中,这一技术有着非常广阔的前景和应用。     

Single-Material OECT-Based Flexible Complementary Circuits Featuring Polyaniline in Both Conducting Channels

The organic electrochemical transistor (OECT) with a conjugated polymer as the active material is the elementary unit of organic bioelectronic devices. Improved functionalities, such as low power consumption, can be achieved by building complementary circuits featuring two or more OECTs. Complementary circuits commonly combine both p- and n-type transistors to reduce power draw. While p-type OECTs are readily available, n-type OECTs are less common mainly due to poor stability of the n-type active channel material in aqueous electrolyte. Here, a complementary circuit is made using a pair of OECTs having polyaniline (PANI) as the channel material in both transistors. PANI, with a finite electrochemical window accessible at voltages lower than 1 V, exhibits a peak in current versus gate voltage when used as an active channel in an OECT. The current peak has two slopes, one n-like and one p-like, which correspond to different electrochemical regimes of the same underlying conjugated polymer. The electrochemistry enables the design of a complementary circuit using only PANI as the channel material. The PANI-based circuit is shown to have excellent performance with gain of ≈7 and is transferred on a flexible biocompatible chitosan substrate with demonstrated operation in aqueous electrolyte.     

A theoretical model for the time varying current in organic electrochemical transistors in a dynamic regime

The dynamic interaction between cations and doped conductive polymer is at the basis of the working principles of organic electrochemical transistor devices. In this letter, we describe a theoretical model for the transport of saline ions in an electrolyte under the influence of an external voltage in a dynamic regime. We show how this scheme can be used to derive the time varying response and current generated by a conductive PEDOT:PSS polymer based OECT device interacting with those ions. The simulated output of the system displays a very high sensitivity on the parameters of the process including charge, size and concentration of the ions, and the frequency of operation of the device. The proposed model can be used to analyze the activity of an OECT device to derive the physical characteristics of individual species in a solution.     

High-Gain Chemically Gated Organic Electrochemical Transistor

Organic electrochemical transistors (OECTs) have exhibited promising performance as transducers and amplifiers of low potentials due to their exceptional transconductance, enabled by the volumetric charging of organic mixed ionic/electronic conductors (OMIECs) employed as the channel material. OECT performance in aqueous electrolytes as well as the OMIECs’ redox activity has spurred a myriad of studies employing OECTs as chemical transducers. However, the OECT's large (potentiometrically derived) transconductance is not fully leveraged in common approaches that directly conduct chemical reactions amperometrically within the OECT electrolyte with direct charge transfer between the analyte and the OMIEC, which results in sub-unity transduction of gate to drain current. Hence, amperometric OECTs do not truly display current gains in the traditional sense, falling short of the expected transistor performance. This study demonstrates an alternative device architecture that separates chemical transduction and amplification processes on two different electrochemical cells. This approach fully utilizes the OECT's large transconductance to achieve current gains of 10³ and current modulations of four orders of magnitude. This transduction mechanism represents a general approach enabling high-gain chemical OECT transducers.     

An Organic Electrochemical Transistor Integrated Photodetector for High Quality Photoplethysmogram Signal Acquisition

The organic photodiode (OPD) is a promising building block for solution-processable, flexible, lightweight, and miniaturized photodetectors, ideal for wearable applications. Despite the advances in materials used in OPDs, their photocurrent and light responsivity are limited, and alternative methods are required to boost the signal response. Herein, a miniaturized organic electrochemical transistor (OECT) is integrated with an OPD module to unlock the potential of OPDs to acquire physiological signals. In this integrated photodetector (IPD) system, the light intensity regulates the OPD voltage output that modulates the OECT channel current. The high transconductance of the OECT provides efficient voltage-to-current conversion, enhancing the signal-to-noise ratio on the sensing site. A microscale, p-type enhancement-mode OECT with high g_m and fast switching speed performs better in this application than depletion-mode OECT of the same geometry. The IPD achieves a photocurrent and responsivity 318 and 140 times higher than the standalone OPD, respectively. It is shown that with the IPD, the amplitude of the photoplethysmogram signals detected by the OPD is enhanced by a factor of 2.9 × 10³, highlighting its potential as a wearable biosensor and to detect weak, often uncaptured, light-based signals from living systems.     

Membrane‐Free Detection of Metal Cations with an Organic Electrochemical Transistor

Alkali‐metal ions, particularly sodium (Na⁺) and potassium (K⁺), are the messengers of living cells, governing a cascade of physiological processes through the action of ion channels. Devices that can monitor, in real time, the concentrations of these cations in aqueous media are in demand not only for the study of cellular machinery, but also to detect conditions in the human body that lead to electrolyte imbalance. In this work, conducting polymers are developed that respond rapidly and selectively to varying concentrations of Na⁺ and K⁺ in aqueous media. These polymer films, bearing crown‐ether‐functionalized thiophene units specific to either Na⁺ or K⁺, generate an electrical output proportional to the cation type and concentration. Using electropolymerization, the ion‐selective polymers are integrated as the gate electrode of an organic electrochemical transistor (OECT). The OECT current changes with respect to the concentration of the ion to which the polymer electrode is selective. Designed as a single, miniaturized chip, the OECT enables the selective detection of the cations within a physiologically relevant range. These electrochemical ion sensors require neither ion‐selective membranes nor a reference electrode to operate and have the potential to surpass existing technologies for the detection of alkali‐metal ions in aqueous media.     

Fast-switching all-printed organic electrochemical transistors

Symmetric and fast (～5 ms) on-to-off and off-to-on drain current switching characteristics have been obtained in screen printed organic electrochemical transistors (OECTs) including PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid)) as the active transistor channel material. Improvement of the drain current switching characteristics is made possible by including a carbon conductor layer on top of PEDOT:PSS at the drain electrode that is in direct contact with both the channel and the electrolyte of the OECT. This carbon conductor layer suppresses the effects from a reduction front that is generated in these PEDOT:PSS-based OECTs. In the off-state of these devices this reduction front slowly migrate laterally into the PEDOT:PSS drain electrode, which make off-to-on switching slow. The OECT including carbon electrodes was manufactured using only standard printing process steps and may pave the way for fully integrated organic electronic systems that operate at low voltages for applications such as logic circuits, sensors and active matrix addressed displays.     

Manipulating the Sensitivity and Selectivity of OECT‐Based Biosensors via the Surface Engineering of Carbon Cloth Gate Electrodes

Organic electrochemical transistors (OECTs) provide the opportunity to fabricate flexible biosensors with high sensitivity. However, there are currently very few methods to improve the selectivity of OECT sensors. In this work, nitrogen/oxygen‐codoped carbon cloths (NOCCs) are prepared by the carbonization of polyaniline‐wrapped carbon cloths at 750 °C under different atmospheres. The resulting NOCC electrodes exhibit different electrochemical sensing behaviors toward ascorbic acid (AA) and dopamine (DA), enabling the fabrication of OECT sensors with high sensitivity and selectivity that are comparable to the state‐of‐the‐art OECT sensors for AA and DA. The structural characterization and theoretical calculation reveal that the electrochemical sensing behaviors of the NOCC electrodes are closely related to their surface compositions, providing an unprecedented strategy for the design of flexible OECT sensors with high sensitivity and selectivity.     

Organic Electrochemical Transistor Common-Source Amplifier for Electrophysiological Measurements

The portability of physiological monitoring has necessitated the biocompatibility of components used in circuitry local to biological environments. A key component in processing circuitry is the linear amplifier. Amplifier circuit topologies utilize transistors, and recent advances in bioelectronics have focused on organic electrochemical transistors (OECTs). OECTs have shown the capability to transduce physiological signals at high signal-to-noise ratios. In this study high-performance interdigitated electrode OECTs are implemented in a common source linear amplifier topology. Under the constraints of OECT operation, stable circuit component parameters are found, and OECT geometries are varied to determine the best amplifier performance. An equation is formulated which approximates transistor behavior in the linear, nonlinear, and saturation regimes. This equation is used to simulate the amplifier response of the circuits with the best performing OECT geometries. The amplifier figures of merit, including distortion characterizations, are then calculated using physical and simulation measurements. Based on the figures of merit, prerecorded electrophysiological signals from spreading depolarizations, electrocorticography, and electromyography fasciculations are inputted into an OECT linear amplifier. Using frequency filtering, the primary features of events in the bioelectric signals are resolved and amplified, demonstrating the capability of OECT amplifiers in bioelectronics.     

Wearable Organic Electrochemical Transistor Array for Skin-Surface Electrocardiogram Mapping Above a Human Heart

Electrocardiogram (ECG) mapping can provide vital information in sports training and cardiac disease diagnosis. However, most electronic devices for monitoring ECG signals need to use multiple long wires, which limit their wearability and conformability in practical applications, while wearable ECG mapping based on integrated sensor arrays has been rarely reported. Herein, ultra-flexible organic electrochemical transistor (OECT) arrays used for wearable ECG mapping on the skin surface above a human heart are presented. QRS complexes of ECG signals at different recording distances and directions relative to the heart are obtained. Furthermore, the ECG signals are successfully analyzed by the devices before and after exercise, indicating potential applications in some sports training and fitness scenarios. The OECT arrays that can conveniently monitor spacial ECG signals in the heart region may find niche applications in wearable electronics and healthcare products in the future.     

On the transient response of organic electrochemical transistors

We present a universal model for the transient drain current response in organic electrochemical transistors (OECTs). Using equivalent circuits and charge injection physics, we are able to predict the drain current in OECT devices upon application of a gate voltage input. The model is applicable to both plain and membrane-functionalized devices, and allows us to extract useful physical quantities such as resistances and capacitances, which are related to functional properties of the system. We are also able to use the model to reconstruct the magnitude and shape in time of an applied voltage source based on the observed drain current response. This was experimentally demonstrated for drain current measurements under an applied action potential.