No abstract

Abstract-The integral nonlinearity (INL) is used for the post-correction of analog-digital converters (ADCs

No abstract

The integral nonlinearity (INL) modeling of pipeline analog-digital converters (ADCs) is investigated in this paper. The INL is divided into two distinct entities: a low code frequency component (LCF) and a high code frequency (HCF) component. Two static models are developed to represent the INL data. In both models, the LCF component is represented by a low-order polynomial. The HCF modeling is performed using two different basis functions: sinc and Gaussian. The structure of both HCF models is motivated by the pipeline architecture of the ADC under investigation. The model coefficients are estimated by applying the least-squares method to the measured INL data from two samples of a commercial pipeline ADC. The estimated HCF models are compared to each other and to previous models presented in the existing literature. In addition, the modeling methods are applied to synthetic HCF data generated by a pipeline ADC simulation model constructed in Matlab. The INL models are then used to calibrate the synthetic ADCs, and the improvements in spurious free dynamic range (SFDR) are compared to those obtained when the ADCs are compensated by the INL data. Furthermore, the capability of the HCF modeling to calibrate a given ADC is tested by using the HCF model to compensate a synthetically generated ADC output in which only the measured HCF sequence and noise are added to the quantization process. The results show that the developed HCF models can achieve virtually complete calibration of the considered ADC.

Integral nonlinearity (INL) is used for the post-correction of pipeline analog-digital converters (ADC)s. An input-frequencydependent INL model is developed for the compensation. 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 signal frequency. The INL model is subtracted from the digital output for post-correction. The static compensation is implemented with a look-up-table (LUT). The dynamic calibration is performed by a bank of frequency domain filters using an overlap-add structure. Two ADCs of the same type (Analog Devices AD9430) are compensated in the first three Nyquist bands. The performance improvements in terms of spurious-free dynamic range (SFDR) and intermodulation distortion (IMD) are investigated. By the proposed method up to 17 dB improvements are reported in favorable scenarios.