Technical note: Signal resolution increase and noise reduction in a CCD digitizer

Increasing output resolution is assumed to improve noise characteristics of a CCD digitizer. In this work, however, we have found that as the quantization step becomes lower than the analog noise (present in the signal before its conversion to digital) the noise reduction becomes significantly lower than expected. That is the case for values of sigma(an)/delta larger than 0.6, where sigma(an) is the standard deviation of the analog noise and delta is the quantization step. The procedure is applied to a commercially available CCD digitizer, and noise reduction by means of signal resolution increase is compared to that obtained by low pass filtering.