Through the study of analog-digital conversion, this AF illustrates the complementarity of electronics and signal processing for the design of information management systems. The operation, simulation and then realization of a "Sigma-Delta" analog-digital converter will be studied. This converter has an excellent behaviour with respect to the quantization error inherent to the analog-to-digital conversion. This good performance justifies its important use in the audio field for consumer applications such as CD recorders. In this AF, we focus on highlighting the link between the theoretical and technical aspects that accompany the design of an electronic system.