The photoelectric yield spectrum test in ultraviolet photoelectron spectroscopy analyzer requires weak photoelectron current detection to reflect the excited photoelectrons. Since the weak current stimulated by ultraviolet irradiation materials is in the order of picoampere, this paper adopts the combination of ADI's ultra-low noise operational amplifier ADA4530-1 and microprocessor STM32F103C8T6. A small current detection circuit based on I-V conversion method was designed with the Guarding ring protection and shielding cable technologies, and with the 24-bit ultra-high resolution ADC device ADS1256 at the back end. Using the Keithley 6221 standard current source to test the designed detectio Research on Low-Level Current Detection in Ultraviolet Photoelectron Spectroscopy Analyzersn circuit, the relative error of the weak current measurement is less than 2%, and the linearity of the whole detection system is good, the coefficient of determination R² is 0.99997, and the resolution can reach 2pA. The results show that in the range of 10 ~ 500pA, the designed weak current detection system can achieve a good picoampere level of weak current detection.

weak current detection,transimpedance amplifier circuit,analog-to-digital conversion