电离规离子流可编程增益放大器的设计

Design of ion current programmable gain amplifier in ionization gauge

采用前置微电流放大器和可编程增益放大器两级运放,实现电离规离子流的可编程增益放大,以满足在真空度迅速变化且动态范围较宽时对真空度的快速准确测量。介绍了微弱电流信号的放大原理、器件选择原则、单片机控制可编程增益放大器的实现方法、电路抗干扰措施等,并给出了部分测试结果。本文设计的电离规离子流放大电路具有增益动态范围宽、精度高、响应速度快等优点,为托卡马克装置的真空度快速测量系统中离子流测量电路提供了设计参考。

To achieve the programmable gain amplification over the ion measurement of the vacuum with a wide dynamic range which changes current of ionization gauge and its quick and accurate rapidly, two-stage operational amplifiers the micro current preamplifier and the programmable gain amplifier （PGA） were used in this paper. Then the design principle of the micro- current amplifier, how to select the circuit elements and the implementation method of the SCM controlling the PGA, the anti- interference measures of the circuit were introduced and parts of the test results have also been given. The design of ionization gauge ion current amplifying circuit in this paper has its advantages of wide dynamic range, high precision, fast response and so on. It could be used for reference to design ion current measurement circuit of vacuum fast measuring system in Tokamak.