Estimation of imperfections of a time-interleaved analog-to-digital converter

A method of operating a time-interleaved analog-to-digital converter for conversion of an analog input signal to a digital output signal having a sample rate R comprises, for each of at least some activations of an array of constituent analog-to-digital converters, defining first and second sets of the constituent analog-to-digital converters, feeding the analog input of each analog-to-digital converter of the first set with a reference value for imperfection measurements and clocking each analog-to-digital converter of the first set with one of the timing signals, feeding the analog input of each of analog-to-digital converter of the second set with the analog input signal for generation of an intermediate constituent digital output signal at the digital output and clocking each analog-to-digital converter of the second set with one of the timing signals, wherein no timing signal is used to clock two or more of analog-to-digital converters of the second set.