High precision three-electrode test circuit based on STM32
YUAN Heng，XV Jun-ming，HU Xiao-ping
（College of Electronic Information，Hangzhou Dianzi University，Hangzhou 310018，China）
Abstract：Aiming at solving problems such as large volume and high prices of three-electrode test products，based on the analysisprinciple of three-electrode，the structure of three-electrode system was designed and a method was presented to build a circuit whichbased on STM32 microprocessor. Test circuit was composed by the potentiostat circuit and voltage amplification circuit. Potentiostatcircuit whose core device was operational amplifiers with high precision was designed，micro-voltage was amplified by difference amplifierwithin-phase parallel structure，and A/D converter with I2C interface was sampled the amplified voltage signal. The results indicate thatthe error of potential is below 1 mV and the circuit can measure current whose value is less than 0.1 μA. The circuit can be used toproduce portable three-electrode test equipment.
Key words：potentiostat；reference voltage circuit；micro-current testing circuit；STM32