Blind Calibration Algorithm for Nonlinearity Correction Based on Selective Sampling

Abstract

This paper proposes a blind calibration algorithm for suppressing nonlinearity in analog-to-digital converters (ADCs). The proposed algorithm does not need any external calibration signal and is first of its kind. The proposed algorithm relies on the properties of downsampling and orthogonality of sinusoidal signals to estimate the nonlinearity coefficients present in the system and can be operated to remove even and odd order nonlinearities simultaneously. The working of the algorithm is demonstrated on a first-order ring oscillator based ΔΣ ADC, whose performance is limited due to the nonlinearity present in its system. Built in 0.13 μm CMOS, the algorithm improves the SNDR of the ADC by 39 dB, while improving SFDR by 45 dB.