Analysis of distortion in A/D converters by time-domain and code-density techniques

Two new methods for measuring the total harmonic distortion of an A/D converter are described. One is based on time-domain analysis, the other on modified code density analysis. Experiments show that these methods give results comparable to the ones provided by FFT analysis. It is then shown, by both experiments on a flash converter and computer simulations, that the conventional code density analysis does not provide accurate signal-to-noise-plus-distortion ratio (SNDR) estimates at the highest frequencies, while the proposed methods do.