A Specific Distortion Pattern of Flash ADCs Identified by Discriminating Time-Domain Analysis

This paper reports a specific error pattern which is observed in several flash analog-to-digital converters (ADCs). The pattern is recognized in reconstructed waveforms like a notch that appears after every peak and bottom of the input. The power of the error is usually so small that it is hard to recognize in the frequency domain, even when the notch is easily visible in the time domain. We have identified the phenomena by elaborate time-domain method that we call “Euclidean reordering.” It is a kind of waveform reconstruction technique with associated techniques that make the method powerful and general for various ADC analyses, not limited for flash ADCs. The one-clock previous wave plot with the reconstructed waveform is one of associated techniques that indicates the dog-tooth positions at their crossings. We assume hysteresis of comparators as its mechanism and show several clues that support the assumption.