Correcting phase error in a two-channel TIADC system in a manner that is independent of the Nyquist zone(s) occupied by the input signal. In the preferred approach this is done using the gradient of a phase error estimate. The gradient may be determined from a simplified expression of linear regression; the direction of the adaptation is then controlled by the sign of the gradient. The adaptive algorithm converges to the optimal value regardless of the Nyquist zone occupied by the input signal.