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恒流电路在电磁测量、电子技术及某些高精密仪器和仪表中,有广泛的应用。不同场合,对恒流源的精度要求亦不同。低精度的恒流源,一般是利用半导体器件(如晶体管、场效应晶体管、恒流管)的恒流特性来实现的,高精度的恒流源一般采用线性放大电路或集成运算放大器并利用负反馈原理进行电压-电流变换。恒流源输出电流的变化,主要由于负载的变化、供电电压的变化、温度的变化、以及元器件(如晶体管、运算放大器、稳压管、取样电阻等)的老化。本文扼要分析几种典型电路的稳流系数、动态内阻及电流温度系数。一、低精度恒流电路最简的恒流电路可由一个元件——恒流管构成,也可以由一个场效应晶体管和一个电阻串接而成。稳压电源中用简单的恒流源代替某些电阻后可使稳定度
Constant current circuit in the electromagnetic measurement, electronic technology and some high-precision instruments and meters, has a wide range of applications. Different occasions, the accuracy of the constant current source requirements are also different. Low-precision constant current source, the general use of semiconductor devices (such as transistors, FETs, constant current) constant current characteristics to achieve, high-precision constant current source generally uses a linear amplifier circuit or integrated operational amplifier and the use of negative Feedback principle of voltage - current conversion. Constant current source output current changes, mainly due to load changes, supply voltage changes, temperature changes, and components (such as transistors, op amps, zeners, sampling resistance, etc.) of the aging. This article briefly analyzes the steady flow coefficient, dynamic resistance and current temperature coefficient of several typical circuits. First, the low-precision constant current circuit The most simple constant current circuit by a component - constant current tube can also be a field effect transistor and a resistor in series. Regulated power supply with a simple constant current source to replace some of the resistance can make the stability