100pA～1μA量程的微弱电流源研制

为了实现对微弱测量仪器进行测试与校准,根据恒流源电路的思想,研制了一种由运算放大器构成的微弱电流源。在微弱电流产生中,利用恒压源和高精度标准电阻,通过V-I变换来实现微弱电流的输出;设计反馈调节网络,来解决普通电流源实现微弱电流输出易受负载影响的缺点,消除负载对输出电流的影响,同时,实现100pA～1μA量程的微弱电流输出。为提高电流源的性能,电路中采取了屏蔽和滤波处理,来解决噪声的影响。经过测试,结果表明该电路的电流范围在100pA～1 μA之间,电流源稳定可靠。在1nA时,误差不超过0.08nA。

Development of Weak Current Source for Currents Between 100pA and 1μA

In order to test and calibrate the measuring instruments for weak current detection, a weak current source for currents between 100 pA and 1μA is developed, on the basis of the principle of  constant-current source.A current source is built with operational amplifiers, resistors, constant voltage and standard resistance values to gain weak current output through V-I converter.A complete analysis for the  dynamic properties of this current source, its equivalent relative error and circuit design are given.The effects of stray impedances on the behavior of the current source are taken into account and the techniques necessary to achieve an optimum stable performance,including processing noise effect are applied.Experiments show that the weak current source is stable and reliable,the output current range of the circuit is 10pA～10μA.In 1nA, the error is less than 0.08nA.