Blind background calibration of harmonic distortion based on selective sampling

This paper proposes a blind calibration algorithm for suppressing harmonic distortion 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 harmonic distortion coefficients. The algorithm can be operated in both foreground and background modes to remove even and odd harmonics simultaneously. The algorithm is demonstrated on a first-order ring oscillator based ΔΣ ADC, whose performance is harmonic distortion limited. Built in 0.13μm, the algorithm improves the SNDR of the ADC by 39dB while improving SFDR by 45 dB.