Background LMS Calibration Algorithm Realization for SAR-ADC

Abstract

In order to minimize the impact of SAR-ADC capacitance weight mismatch on conversion accuracy, a digital calibration algorithm applied to SAR-ADC is implemented based on sub-binary technology and perturbation technology. A Subradix-2 SAR-ADC model was established with Simulink. The LMS adaptive calibration algorithm was used to calibrate the output iteratively, and the algorithm was implemented on FPGA Xilinx Spartan-6 device. The results show that when the input signal frequency is 239.19kHz and the sampling frequency is 1MS/s, the ENOB is increased from 9.57 bit to 11.78bit.