A Background Timing Skew Calibration for Time-Interleaved ADCs Based on Frequency Fitness Genetic Algorithm

This article presents a background calibration method for timing skew in time-interleaved (TI) analog-to-digital converters (ADCs). The timing skew is detected by the frequency fitness genetic algorithm (FFGA) and compensated by digital finite impulse response (FIR) differentiators. This method does not require any reference channel and can converge the estimated timing skew in each channel independently. Compared with conventional calibration methods, the convergence time of this method has been reduced by several times. As a chromosome contains multiple estimated timing skew values, this method can be extended to an arbitrary interleaving factor. The all-digital structure applies to advanced technology processes. The effectiveness of the proposed method is presented through numerical simulation and measurement results. It shows that after timing skew calibration, the spurious free dynamic range (SFDR) and signal-to-noise and distortion ratio (SNDR) of a commercial 3.6-GS/s four-channel TI-ADC are improved by 29.5 and 16.9 dB, respectively.