Elimination of quantization effects in measured temporal noise

This paper presents a mathematical analysis of how temporal noise is transformed by quantization. A new method for measuring temporal noise with a low-resolution ADC and then accurately refer it back to the input of the ADC is shown. The method is, for instance, applicable to CMOS image sensors where photon shot noise is commonly used for determining conversion gain and quantum efficiency. Experimental tests have been carried out using a custom designed CMOS image sensor with an on-chip ADC featuring programmable gain and offset. The measurements verify the analysis and the method, e.g. noise levels of 0.11 LSB was measured with an accuracy 30 times higher than a traditional method would give.