A Correlation-based Timing Skew Calibration Strategy Using a Time-Interleaved Reference ADC

Abstract

Reference ADC based timing skew calibration is an effective method to eliminate the timing skews of time-interleaved ADC (TIADC). However, at an extremely high sampling frequency such that the reference ADC cannot operate at the full speed, these kinds of methods would have a problem of periodically time-varied input impedance. In this paper, an improved correlation based timing skew calibration technique is proposed, which replaces the conventional single channel reference ADC to a full speed operated time interleaved reference ADC (TIRADC) to mitigate the time-varied input impedance problem. The paper theoretically demonstrates that if a proper time interval is set between the sampling edges of TIADC and TIRADC, then the timing skew of TIRADC itself will not interfere with the timing skew calibration of TIADC. The proposed timing skew calibration strategy is verified in MATLAB by modeling a 13-bit 8-way TIADC with a 1-bit 3-way TIRADC, simulation results well confirm the correctness of the proposed timing skew calibration strategy.