A procedure for highly reproducible measurements of ADC spectral parameters

The evaluation of spectral parameters characterizing analog-to-digital converters (ADC) can be addressed by employing both parametric and non-parametric techniques. Whatever the adopted testing techniques, the IEEE standards 1057 and 1241, which list the most effective ADC testing procedure, recommend the use of coherent sampling. Such a condition can not be guaranteed a priori with respect to spurious tones eventually present in the ADC output spectrum and data windowing is usually employed to reduce these phenomena. However, standards do not provide clear criteria for choosing the window that assure the maximum parameter estimation accuracy. The European draft standard Dynad suggests the employment of one out of seven optimal windows, in accordance to the ADC resolution. However, each sequence is characterized by distinctive parameters. Thus test automation may be reduced. In this paper the use of a class of windows that are defined by setting the mainlobe width value and that can be easily calculated by employing standard computational tools is proposed. Such sequences maximize also the estimation accuracy for any given ADC resolution, thus improving both measurement reproducibility and test automation. Experimental results that validate the effectiveness of the proposed window class are presented.