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| Development of Weak Current Source for Currents Between 100pA and 1μA |
| LEI Sheng-jie,WEI Zhi-yong,FANG Mei-hua,CHEN Guo-yun,ZHANG Zi-xia,HUANG San-bo |
| Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu 210016, China |
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Abstract 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.
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2013, Vol. 34 
