Blind estimation of timing errors in interleaved AD converters

Parallel A/D converter structures is one way to increase the sampling rate. Instead of increasing the sample rate in one A/D converter, several A/D converters with lower sampling rate can be used instead. A problem in these structures is that the time between samples is usually not equal because there are errors in the delays between the A/D converters. We present a method to estimate the timing offset errors. The estimation algorithm works without any special calibration signal, instead the normal input signal is used. The only assumption that we need on the input signal is that most of the energy is concentrated to a low pass band, below about 1/3 of the Nyquist frequency. Simulations of the time-interleaved A/D converter show that the method estimates the errors with high accuracy.