Choice of the cosine-class windows for ADC dynamic testing by spectral analysis

The cosine-class windows are some of the most used windows in analog-to-digital converter (ADC) dynamic testing by spectral analysis when the coherent sampling condition cannot be fulfilled. The DYNAD European draft standard is the only one which gives some suggestions for the proper choice of some windows belonging to this class. In DYNAD the effectiveness of a window in spectral leakage reduction is evaluated by means of the resolution of an ideal ADC up to which the window is still efficient, but only when the fractional part of the recorded sinewave cycles is equal to 0.5, i.e. for the worst case. In this paper a more comprehensive analysis than the one done in the DYNAD draft standard is presented. The effective number of bits of an ideal ADC up to which the window remains efficient is determined as a function of the fractional part of the recorded sinewave cycles and of the power of spectral leakage. Simulations confirm the conclusions drawn from the analysis presented in the paper.