A method detects a threshold crossing instant at which a signal crosses a threshold, by: sampling the signal at plural sampling instants spaced from one another by a sampling period; detecting consecutive first and second sampling instants at which the signal has a first signal value lower than or equal to the threshold, and the signal has a second signal value higher than the threshold, respectively; calculating a first interval indicative of a time between the threshold crossing instant and the first sampling instant; setting a reference signal having a reference amplitude representing the first interval relative to a reference scale; generating a signal with a delay depending on said reference signal; generating a threshold crossing detection signal at an instant delayed by a second interval; calibrating the reference scale of the reference amplitude so that the second interval is substantially equal to the first interval.