Apparatus and associated methods relate to modulating polarity on sample outputs from a time-interleaved analog-to-digital converter (TIADC) as an input to a time skew extractor in a clock skew calibration control loop. In an illustrative example, a multiplier-mixer may impart a polarity change to every other data sample transmitted between the TIADC and the time skew extractor. In some examples, a multiplexer may select between the polarity modulated samples and non-polarity modulated samples before the multiplier-mixer. Selection between the polarity modulated samples and the non-polarity modulated samples may be based on, for example, determination of specific frequency bands of an analog input signal. Various embodiments may improve convergence of clock skew calibration control loops for analog input signals sampled with a TIADC near a Nyquist
