A digital-mixing-based method for timing skew estimation in time-interleaved ADCs

Abstract Time-interleaving has been a popular choice for multi-GHz analog-to-digital converters (ADCs). Unfortunately, inherent defects such as offset, gain, timing-skew mismatches among sub-ADCs degrade overall performance seriously. At present, the method for eliminating offset and gain mismatch is fairly straightforward, however, calibration for timing-skew is still in a state of exploration. An efficient digital-mixing-based method to estimate timing skew in time-interleaved analog-to-digital converters (TI-ADCs) is proposed and verified. The timing skew can be estimated by digital-mixing and inverse sine function processing. The proposed method can greatly alleviate the effects of phase ambiguity. It is also insensitive to offset mismatch. A four-channel TI-ADC behavioral system of 10-bits 2GS/s has been simulated to verify the performance of the method. Simulation results demonstrate that the method greatly improves the TI-ADC’s performance and is effective up to the severe timing skew mismatch.