A Fast Convergence Second-Order Compensation for Timing Skew in Time-Interleaved ADCs

This brief presents a digital background calibration technique for timing skew in time-interleaved (TI) analog-to-digital converters (ADCs). It updates the calibration step adaptively based on the detection error. This results in large update step initially, and it reduces with the calibration cycle going on. More than two times convergence time is saved compared with the conventional fixed update step method. Besides, by extending the compensation to second-order, both calibration range and accuracy are improved. To demonstrate the effectiveness of the proposed timing skew calibration, extensive simulation and measurement results are provided. It shows that after timing skew calibration, the signal-to-noise and distortion ratio (SNDR) and spurious free dynamic range (SFDR) of a two-channel prototype TI ADC are improved by 8.2 and 14.9 dB, respectively.