Integral Nonlinear Fitting and Calibration of High Precision Analog-Digital Converters

Integral nonlinearity is an important parameter affecting the performance of Analog-Digital Converters(ADC). And the integral nonlinearity (INL) is used for the calibration of analog digital converter. In order to let high precision ADC perform excellent performance indicators, In this paper, we propose a method based on quadratic functions to piecewise fit and calibrate the nonlinear error of the high precision analog to digital converter chip (Analog Devices AD9680). The model consists of a static term that is dependent on the ADC output code and a dynamic term that has an additional dependence on the input frequency. Test results show that within the bandwidth of 200MHz, Spurious Free Dynamic Range, Signal to Noise and Distortion Ratio, Effective Number of Bits and other indicators of ADC were got better improvement. In addition, this calibration algorithm has a certain universality, the calibration algorithm is expected to apply to all pipelined ADC.