Abstract:
In the liquid chromatography system, the absorbance values obtained by Lambert Beer’s law will be transformed from digital to analog, which will be sent to the chromatography workstation for analysis. However, multi bit sigma delta modulators based on the data weighted averaging (DWA) technique are plagued by extra harmonic noise, which will affect the performance of chromatographic signals. This paper presents an optimized DWA algorithm, which can suppress harmonic noise and improve the DAC performance. Different from the conventional DWA method, a condition selected block is added in the proposed algorithm to control the initial pointer value in each selection cycle such that the harmonic noise can be avoided. The simulation results show that the harmonic noise can be significantly attenuated, and DC characteristics can be effectively raised such that the proposed algorithm is more benefit for the chromatographic signal processing.