The conversion of an analog signal to digital quantizes the input in both time and
amplitude [1]. Quantization in time is referred to as sampling and is performed in the
ADC front-end, often by an explicit track-and-hold circuit. The amplitude quantization,
referred to just as quantization, approximates the input signal given a set of fixed
reference levels. The number of possible quantization levels determines the resolution
of the ADC, which is typically described with the number of binary bits, n, needed to
represent the quantization level.