Mutual information and time-interleaved analog-to-digital conversion

Analog to digital conversion is often a critical component of a digital communication link. However, the figures of merit that are used in the design of the components that comprise this step are more appropriate for signal reconstruction applications than for digital communication. This paper considers the design of time-interleaved analog-to-digital converters using the mutual information between the transmitted symbols and the outputs of the paths of the converter as a design criteria. Specific attention is paid to the sensitivity of the mutual information through the converter as a function of the relative sampling phases of the time-interleaved samplers. Mutual information is evaluated for a variety of converter strategies, channel conditions, and noise sources. It is shown that for oversampling converters, the optimal sampling phases not in general equispaced, as is conventionally assumed in converter design.