共查询到19条相似文献，搜索用时 171 毫秒
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一、前言目前,市场上A/D转换器虽种类繁多.但将多通道转换、采样/保持和模数转换功能集成到一起的12位A/D转换器,却非常少,美国美信公司研制出一种集成12位串行A/D转换器MAX186,将8通道模拟开关、大带宽跟踪/保持电路、A/D转换器和移位寄存器集成到一片20脚双列直插芯片上,消除了从输入信号到A/D转换器的一些中间环节的传输误差,大大提高了采样精度和转换精度,灵活的串行接口使其易于与微处理器接口。二.MAX186的功能及特点 1.内部结构及特点 MAX186内部集成了8通道模拟开关、大带宽跟踪/保持电路、逻辑控制单元、时钟控制单元、A/D转换器和移位寄存器,为20脚双列直插芯片,具有体积小、转换速度快、转换精度高(满量程相对精度± 相似文献
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AVR单片机自带10位精度A/D转换器,本文基于Proteus软件对AVR单片机的A/D转换进行仿真设计,使得抽象的A/D转换变为形象的数据显示.通过对A/D转换的仿真介绍,展示了利用仿真软件对单片机资源进行仿真和分析的方法和步骤. 相似文献
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A/D转换器是数字化测量和显示仪表的重要组成部分,其转换速度、精度和分辨率,直接影响着测量结果和显示的质量指标.本文针对常用的多斜式、多周期式、循环余数武、脉宽转换式、双斜武等几类A/D转换器,从原理和结构上进行了具体地分析,以便于在ND转换电路设计中ADC的选择和采用元器件组装A/D转换器时,选用合适的A/D转换方式. 相似文献
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介绍了一种基于单片机的电压自动调整系统设计,给出了系统总体设计方案,并针对设计中的重点电路,单片机电路、A／I）转换电路、D／A转换电路、显示电路以及串口通信电路进行了详细介绍,通过实际系统测试,给出了测试结果,验证了该系统的设计的正确性. 相似文献
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主要介绍一种A/D转换芯片静态参数测试电路,该测试电路的设计基于A/D静态参数测试的直方图法,同时PC机上运行的Labview测试程序控制PC机并口通过EPP协议与该测试电路通讯,获得测试数据,完成参数运算。 相似文献
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结合广泛使用的TLC549串行A/D转换器,采用FPGA器件EPIC6Q240C8,对A/D转换芯片TLC549进行采样控制.整个设计在Quartus Ⅱ平台下进行软件编程和下载.采用VerilogHDL语言描述,实现正确的TLC549转换的工作时序控制过程.该设计可用于信号采集和实时监控方面,仿真结果和实际运行显示该模块工作性能稳定、可靠性高,使用方便. 相似文献
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飞速发展的宽带数字接收机技术的瓶颈是实现器件的低速处理能力不能适应超高速ADC产生的超高速数据速率,常用的基于多相滤波的数字信道化方法和数字下变频方法形成的较低数据速率不能适应对宽带信号的处理。本文提出了用多路并行的方式将大规模FPGA内相对丰富的资源在低速率下合并为超高速处理的方法。在现有的工作速率为500 MHz以下的FPGA器件上实现了4.8GHz的超高速混频和超高速滤波,可满足信号带宽500 MHz的实时处理需求。 相似文献
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《Journal of The Franklin Institute》2019,356(13):6875-6898
This paper proposes an improved passivity-based control (PBC) technique to provide accurate coordination between AC and DC sides of a grid-tied AC/DC hybrid microgrid. The proposed PBC is based on the passive properties of the system and the energy exchange between the subsystems. To this end, three mathematical formulations for the converters are driven in the first step. Then, using the formulations, the impedance injection is applied to shape the error dynamics of all DC/DC and DC/AC converters. The DC link-connected DC/AC converter is used to help the AC side for maintenance of the power quality factors such as, the grid frequency and voltage magnitude in the presence of any unbalanced power load sharing. The first contribution of the paper is the part of impedance injection to the DC/AC converter, which aims to provide more decoupling and faster convergence rate for both the steady states and the dynamical conditions. Secondly, a Lyapunov function is defined for converters’ error dynamics that provide more accurate statement of the proposed damping injections. Besides, as an attractive control feature, decoupling properties of the suggested method are investigated. Then, through achieving several curves, various operating conditions of DC/DC and DC/AC converters under varying the system errors and proposed damping injections are evaluated as well. For the purpose of validation, the system under study is simulated in the MATLAB/SIMULINK software package against a variety of system errors and converters’ operational conditions. 相似文献
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In this paper, we report a new method to incorporate 3D scaffold with electrotaxis measurement in the microfluidic device. The electrotactic response of lung cancer cells in the 3D foam scaffolds which resemble the in vivo pulmonary alveoli may give more insight on cellular behaviors in vivo. The 3D scaffold consists of ordered arrays of uniform spherical pores in gelatin. We found that cell morphology in the 3D scaffold was different from that in 2D substrate. Next, we applied a direct current electric field (EF) of 338 mV/mm through the scaffold for the study of cells’ migration within. We measured the migration directedness and speed of different lung cancer cell lines, CL1-0, CL1-5, and A549, and compared with those examined in 2D gelatin-coated and bare substrates. The migration direction is the same for all conditions but there are clear differences in cell morphology, directedness, and migration speed under EF. Our results demonstrate cell migration under EF is different in 2D and 3D environments and possibly due to different cell morphology and/or substrate stiffness. 相似文献
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M.R.D. Al-Mothafar 《Journal of The Franklin Institute》2012,349(1):260-283
A procedure is established for the small-signal modelling of n-connected current-programmed parallel-input/series-output pulse-width modulated bridge-based buck dc–dc converters operating in the continuous-current conduction mode. State-space averaging is used to represent the power stage while current-mode control is modelled using a modified new continuous-time technique. Approximate analytical expressions of the major small-signal transfer functions that include the number of modules as a variable are proposed. PSpice simulations are carried out to validate the analysis. 相似文献
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技术溢出速度预期、竞业避止与研发力度 总被引：1，自引：0，他引：1
创新企业在做研发资源投入决策时，它对其技术创新溢出到竞争对手速度的预期直接影响它的研发资源投入水平，本文认为创新企业相应的预期主要基于自然不可控溢出和有限可控溢出二种变量；构建了技术创新溢出速度预期、市场竞争结构与研发力度的关系模型；当企业和国家相关法律环境有能力使有限可控溢出发挥作用的时间滞后，使之和自然不可控溢出叠加后的溢出时间接近于技术创新获利的时效期时，将会使得创新企业的研发决策更多地基于技术创新本身特征；竞业避止政策直接影响有限可控溢出作用的时间和强度。其期限的设定是由技术创新获利时效期、自然不可控溢出速度和竞业避止政策实施成本等变量综合决定。 相似文献
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Alireza Goudarzian Adel Khosravi Heidar Ali Raeisi 《Journal of The Franklin Institute》2019,356(15):8569-8594
This paper proposes a unified method to design an optimized type of the hysteresis modulation-based sliding mode current controller for non-minimum phase power converters in continuous conduction mode. The traditional sliding mode controlled converters have a slow transient voltage response at heavy loads, a large overshoot at light loads and during abrupt output resistance variations. To solve these problems, an optimized feedback control scheme is used according to the output resistance to adjust the coefficients of the controller. The basic idea of this controller is to suggest a new way for reduction of the sensitivity function amplitude of the closed loop system. The presented approach is developed for three basic DC/DC converters; i.e. boost, buck-boost and quadratic boost converters. Generally, the certain advantages of the suggested control approach are: (i) a fast transient response can be achieved in heavy load conditions, (ii) the voltage overshoot can be effectively reduced during load variations; (iii) the transient voltage overshoot can be eliminated in light load conditions; (iv) the closed loop control sensitivity can be reduced and therefore, the performance specification of a control system can be improved compared with the conventional sliding mode current control. To show the reliability of the suggested control scheme, simulations and experimental results for the derived systems are developed. Several conditions are performed to confirm the effectiveness of the proposed controller. 相似文献