Uncertainties in quantization-noise estimates for analog-to-digital converters

Estimates of quantization noise, obtained by stimulating an ideal analog-to-digital converter with a sine wave contained in the input range, are affected by an appreciable uncertainty, which may affect SNR and ENB specifications, especially in the case of low resolution devices. The uncertainty can be eliminated, when possible, by the use of an input sine wave bringing the converter into saturation. The different effects of additive noise on the noise estimates obtained by the various test procedures are also discussed, showing, in particular, that quantization noise may be overestimated by histogram testing with a nonsaturating input sine wave. Therefore, any noise specification should clearly make reference to the test signal parameters and to the instrumentation characteristics.