Efficient Time-Skew Calibration for Time-Interleaved ADC via Matrix Binary Decomposition and Increment-Based Adaption

A fully digital background time-skew calibration technique for time-interleaved analog-to-digital converters (TI-ADCs) is presented in this brief. Interleaving errors due to time-skew are modeled as additive error terms through first-order Taylor expansion and are corrected by finite impulse response (FIR) differentiators. Computational complexity is substantially reduced by leveraging matrix binary decomposition technique. Furthermore, the increment-based adaption technique is employed to accelerate the convergence of coefficients estimation while maintaining low steady-state error. Both theoretical analysis and experimental results demonstrate that the proposed approach offers lower computational complexity and faster convergence compared to conventional methods. The proposed method is applied to an 11-bit, 3.5 GS/s, 8-channel time-interleaved SAR ADC fabricated in 28-nm CMOS. Measurement results show that the proposed calibration method improves the SFDR by 16.66 dB and the SNDR by 10.45 dB at low frequency, and by 20.6 dB and 17.4 dB at the Nyquist frequency, respectively.