Design of FPGA-based spectrometer dynamic baseline compensation system
Yu Chenghao，Xue Meng，Shi Langjie，Guo Hanming
School of Optical-Electrical and Computer Engineering， University of Shanghai for Science and Technology
Abstract： The linear array CMOS photodetector sensor possesses advantages such as high sensitivity, a wide spectral response range, low power consumption, and a compact size. It is widely used in the development of portable spectrometers. To address the issue of baseline drift caused by the increasing dark current of the CMOS image sensor, a dynamic baseline compensation system based on FPGA for the spectrometer is designed. The system utilizes reserved pixels on the sensor to calculate the baseline value for each frame in real-time and provide feedback. It employs high-performance operational amplifiers, differential amplifiers for voltage tracking, baseline compensation circuits, and single-ended to differential circuits to process the CMOS analog signals and perform high-speed A/D conversion. A precision DAC chip is used to provide real-time dynamic feedback for baseline compensation values.The final test results demonstrate that as the integration time increases, this design consistently maintains a lower baseline level for spectral data. The system's circuit design is flexible, it ensures accurate spectral data acquisition, and it effectively controls the baseline, making it well-suited for detecting weak spectral signals.
Key words : spectrum acquisition；line-array CMOS；FPGA；baseline compensation；signal processing
