A kind of charge integration amplifying circuit for radiation-measuring device

Micro-current whose value is less than 1uA is an important kind of expression form of the interaction between radial and matter. In this paper, three kinds of micro-current measurement method were compared at first. Then, a pA level current measurement system designed with capacitor integration method used in radial test was described. The basic design principle and its calculation formulas such as low cut-off frequency, high cut-off frequency, noise characters and drift characters in the paper were mentioned in detail. The key points during researching such as cancelling leakage current, making PCB with special materials, cleaning PCB, phase compensation and noise suppression method were also mentioned. At last, the calibration method for the system was explained step by step. The precision of our system in micro-current test was calculated according to the test results. The system's precision in micro-current measurement is about 1%. In the conclusion section, the work of dissertation is summarized and prospect of improving direction of system is presented. Nowadays, the system has also been used in the calibration of PD (partial discharge) calibrator which is the most important device in PD test. As research continues, more and more application Fields with our system will be found.