Development of a device for picoampere currents measuring

One of the actual topics in microelectronics is the problem of measuring small currents. We have considered possible solutions to this problem, one of which is a current measurement method based on the use of an amplifier with differential inputs. The advantage of this scheme is that the high-precision measuring resistance is divided between two identical elements that are physically installed in the same orientation and at the same distance from the source of magnetic interference. Interference induced on two resistors in this case creates the same signals, which are suppressed at the output of the amplifier. To solve this problem, we have developed a stand for testing a device for measuring picoampere currents. The stand consists of a measuring unit, a digital-to-analog converter module and special software. The measuring unit consists of a differential amplifier stage, followed by a signal amplification circuit on an operational amplifier, the digital-to-analog converter module is implemented on the basis of an external input-output module L-CARD E20-10, and the L-Graph program was used for signal processing. As a result of the experiments, the ranges of measured values were confirmed.