Patent ID: 8159377

Claim:
A method of estimating timing skew, comprising: performing, on the output of a plurality of interleaved analog-to-digital converter circuits (ADCs), including a reference ADC, a gradient loop from a block of samples of a particular size, the gradient loop including: empirically determining a cross-correlation of the digital output between adjacent ADCs, including determining a cross-correlation between a last among the plurality of ADCs and a first of the plurality of ADCs, determining a cost function for each of the plurality of ADCs, except the reference ADC, as a square of a difference between adjacent cross-correlations, and determining a gradient for each of the plurality of ADCs, except the reference ADC, that is proportional to the derivative of the corresponding cost function of each of the plurality of ADCs, except the reference ADC; determining an initial estimate of a timing skew of each of the plurality of ADCs, except the reference ADC, as the product of a function of the gradient of each of the plurality of ADCs, except the reference ADC, and a step size; correcting the output of each of the plurality of ADCs, except the reference ADC, based on the initial estimate of the timing skew of each of the plurality of ADCs, except the reference ADC; and determining a converged estimate of the timing skew of each of the plurality of ADCs, except the reference ADC, by: continually performing on the output of the plurality of interleaved ADCs, including the reference ADC, the gradient loop on additional blocks of samples of the particular size, continually determining a subsequent estimate of the timing skew of each ADC, except the reference ADC, as the sum of an immediately previous estimate of the timing skew of each ADC, except the reference ADC, and a product of a function of the gradient of each of the plurality of ADCs, except the reference ADC, and the step size, and continually correcting the output of each of the plurality of ADCs, except the reference ADC, based on the continually determined subsequent estimate of the timing skew of each of the plurality of ADCs, except the reference ADC.