含有理想电压源的节点电位法解题初探

坚含有理想电压源支路的电路提出了用节点电位法解题的三种不同方法。     

用模拟电压控制数字电位计

本文描述了一个用模拟电压通过设备的I2C接口控制数字电位计的设计。MicrochipPIC12F683微控制器中的ADC将模拟电压转换为控制MaximDS1803数字电位计的I2C流（图1和参考文献1）。在该微控制器的六个I/O通用引脚中,两个引脚控制SDA（系统数据）和SCL（系统时钟线）输出信号，一个控制一只LED，一个接收模拟输入信号。SDA和SCL直接连接到数字电位计的SDA和SCL引脚，分别通过两个4.7kΩ上拉电阻接到VDD。通过接通或断开跳线，可将共用的VCC和VDD分开，并将SDA和SCL隔离。     

降低精密放大器的电压失调

本文对精密放大器的电压失调误差进行分析,并给出了基于电阻网络解决方案,分别提供了分立和集成方案。     

利用电压基准产生稳定流入电流源

正无源元件长期测试用模拟电路,比如0.1%公差电阻或高强度白光LED,经常需要恒流。利用两个运算放大器和一个电压基准,你就能开发出一种提供恒定流入电流源,其可变设定范围是0mA至0.99A。图1所示电路使稳定电     

高精密电压源设计与实现方法

针对标准电压源的高失调性、低稳定性等缺陷,提出了一种高精度精密电压源的实现方案。通过标准电压源的生成过程分析基准电压源对数模转换器的要求,进而选择20位高精度数模转换器AD5791。重点阐述了其电路的设计方案,并结合AD5791的硬件特性和软件设置克服了以往数模转换器作为基准源的高失调现象。对实验数据进行测试表明,该方案具有线性度高、稳定性好的优点,能输出0~10 V连续电压且其输出精度可达0.02mV,线性度高达99.996%,能够满足高精密电压源的设计要求。     

为全景电位计电路增加简单的禁用功能

在混音应用中,一个经常需要的功能就是将一个单声道或单通道音频源混到一个立体声场中.音频工程师所说的一个全景电位计电路是一种可从一个单声道信号产生具有标准波幅的左、右信号并能将信号的声像放在立体声场中任何位置的电路,由于声像的音量似乎与其最终位置无关,产生的左、右信号必须相加,以获得一个恒定功率的信号,而不是一个恒定电压的信号.     

高精密程控电压源设计与实现

提出一种基于MCU的高精密程控电压源实现方法。PC机通过异步串口与MCU通信,远程控制D/A输出,同时使用精密电阻衰减网络压缩电压幅度,提高输出电压精度,输出电压经放大器驱动输出,增强了负载能力。根据大量的测试数据,创造性地拟合输出电压与配置电压值的函数关系,并通过软件修正系统误差和非线性误差,精度可达±1.5μV,完全满足设计要求。     

基于数字电位器的可编程电压基准源设计

在电子设计中为了灵活准确地设置电压基准值,设计了可编程电压基准源电路。详细阐述了电路的设计思路和工作原理。利用5片2.048 V带隙电压基准源芯片串联产生10.24 V电压作为基准。随后创新地利用单片机控制1024抽头的数字电位器对基准电压进行分压,结合精准运放的反向放大电路,最后输出-10.24 V到10.22 V的可编程精准电压值,输出电压分辨力达20 mV。测试结果表明,该电路具有输出线性度好、精度高、性能稳定等优点。     

A precision reference voltage source

With increasing temperature the base-emitter voltage of a transistor with a constant current decreases, while the difference in base-emitter voltages of two identical (integrated) transistors having a constant current ratio increases. From the sum of the two voltages a nearly temperature- independent output voltage is obtained if this sum equals the gap voltage of silicon. A reference voltage source of 10 V based on the principle is described. The reference part of the circuit is an integrated circuit, and thin-film resistors with a small relative temperature coefficient are used. An operational amplifier and a few resistors and capacitors complete the circuit. The source has a parabolic temperature characteristic and the temperature peak can be controlled by resistor adjustment. A change of /spl plusmn/10 K in respect of the peak temperature causes an output voltage change of -250 /spl mu/V, while a change of /spl plusmn/30 K causes a change of -2.2 mV. A long-term stability of 10 ppm/month was measured. The circuit can compete with the best available Zener diode sources, and has the added advantage that practically no selection is necessary.     

Stable voltage reference sources

A family of well-regulated voltage references are shown, which are readily integrable for use with emitter-coupled logic, threshold logic, or linear circuit arrays. By relying on the relatively well-matched characteristics and the temperature tracking of integrated transistors and resistor ratios, the circuit can provide a large range of output fractions of the power supply. The relationships of the circuit components for various output voltages are derived. One circuit configuration gives fractions of the power supply of less than /SUP 1///SUB 2/ while another configuration gives fractions of the power supply greater than /SUP 1///SUB 2/. Limitations of the obtainable fractions are given. Experimental results are shown for each of the two basic circuit configurations and the temperature stability is demonstrated. Well-defined stable voltages are thus derived with a minimum of components and power drain.     

A useful modification of the technique for measuring capacitance as a function of voltage

Measurements of small signal capacitance as a function of applied bias voltage are widely used for the determination of information about metal-insulator-semiconductor (MIS) capacitors. The information that can be derived from the measurements includes interface-state density and flat-band charge density at the insulator-semiconductor (IS) interface, semiconductor doping, and charge stability under bias-temperature stress. A limitation on the use of this measurement method which has until now prevented its even more general application is the requirement that in order to determine Cs, the semiconductor space-charge capacitance, with reasonable accuracy the ratio of Csto CI, the insulating layer capacitance, must be ∼ 10. In the present work it is shown that a modification of the usual method can significantly relax this restriction and allow the accurate determination of Cswhen the ratio Cs/Cris as large as 100 or more, In fact, the inherent limit is no longer directly dependent on this ratio but on the noise level in the capacitance measurement. In some cases Cs/CI≥ 1 due to a thick insulating layer, A very large bias voltage is then required to span the capacitance range of interest; commercially available capacitance meters which typically have applied bias capabilities of ±600 V or less may be inadequate. A simple circuit modification has been employed to allow much larger bias voltages (up to ± 7 kV in the present Work) to be applied to the sample without alteration of or damage to the capacitance meter.     

Wideband precision current sources for integrated circuits

This article introduces two new configurations for precision current sources and current mirrors. Both circuits use n-p-n bipolar devices, but one provides a current source while the other provides a current sink. This permits the use of current sources in IC designs implemented with processes that do not allow p-n-p devices. Analog building blocks such as voltage-to-current converters, active loads, and sink and source current mirrors can be constructed from the new circuits using only n-p-n devices. Furthermore, because these circuits achieve the required precision without the use of high-gain amplifiers, the bandwidths of the circuits are large compared to conventional configurations. The source currents are dependent on a single reference voltage and exhibit good temperature sensitivity.     

MOPA结构准分子激光电源的高精度电压控制研究

为了减小激光器双腔放电时间的相对抖动、稳定激光器输出能量,采用闭环控制回路电压泄放方法,设计了一套主振荡功率放大结构准分子激光谐振充电高精度电压控制方案。通过对电容电压取样处理,动态监测储能电容电压,当电容电压大于目标电压时,由泄放电路泄放电压至目标值,得到高精度的充电电压,使用此电压控制方案后,充电电压的波动由1.67减小到0.83。结果表明,该方案很好地提高了谐振电源储能电容上的电压精度,减小了激光器双腔放电时间的相对抖动,并为后期的激光器能量输出稳定控制打下良好基础。     

An adaptive current tomograph using voltage sources

An adaptive electric current tomography system that contains a novel front-end analog architecture was developed. Programmable voltage sources were used to deliver currents into the study object and to avoid the difficulties of obtaining high-quality current sources. Through inverting an admittance matrix, the system is capable of achieving a desired current drive pattern by applying a computed voltage pattern. The tomograph, operating at 9.6 kHz, comprises 32 driving electrodes and 32 voltage measurement electrodes. The study of system noise performance shows high SNR in the data acquisition which is enhanced by a digital demodulation scheme. In vitro reconstruction images have been obtained with the data collected by the tomograph     

Bandgap voltage reference sources in CMOS technology

Two configurations are proposed for the implementation of bandgap reference sources in CMOS technology. The circuits presented are capable of high temperature operation, and allow a choice of the positive supply rail, the negative supply rail, or ground as the reference point.     

精密高压稳压电源的研究与设计

介绍了用于新型电子束曝光机的30 kV精密高压稳压电源。该电源系统采用了直接调整和间接调整相结合的双闭环调整方案,采用了集中补偿和分散补偿相结合的系统补偿方式,成功地解决了既有高静态精度又有高动态稳定性的问题。为了保证高精度、高稳定性和低纹波电压等技术指标的实现,采取了多项合理的特定电路设计。针对电源系统输出直流高压这一特点,对关键技术采取了针对性的切实有效的技术处理,从而满足了高压电源的高可靠性和长期高稳定性的性能要求。各项技术指标均达到或超过原设计要求。     

一种中速高精度模拟电压比较器的设计

设计一种中速高精度模拟电压比较器,该比较器采用3级前置放大器加锁存器和数字触发电路的多级结构,应用失调校准技术消除失调,应用共源共栅结构抑制回程噪声干扰;应用数字触发电路获得高性能数字输出信号,设计采用0．35μm5VCMOS工艺实现一个输入电压2．5V、速度1MS／s、精度12位的逐次逼近型MD转换器。Hspice仿真结果表明：在5V供电电压下,速度可达20MHz,准确比较0．2mV电压,有效校准20mV输入失调,功耗约1mW。     

一种中速高精度模拟电压比较器的设计

设计一种中速高精度模拟电压比较器,该比较器采用3级前置放大器加锁存器和数字触发电路的多级结构,应用失调校准技术消除失调,应用共源共栅结构抑制回程噪声干扰;应用数字触发电路获得高性能数字输出信号,设计采用0.35μm 5 V CMOS工艺实现一个输入电压2.5 V、速度1 MS/s、精度12位的逐次逼近型A/D转换器.Hspice仿真结果表明:在5 V供电电压下,速度可达20 MHz,准确比较0.2 mV电压,有效校准20 mV输入失调,功耗约1 mW.