Sigma-Delta Converters: Practical Design Guide, 2nd Edition

2 Taxonomy of Architectures

This chapter presents an overview of practical topologies for the implementation of modulation. The large variety of existing realizations is classified according to the type of modulator architecture (single‐loop or cascade), the circuit techniques employed (discrete‐time or continuous‐time), and the nature of the signals being converted (low‐pass or band‐pass). Starting with discrete‐time low‐pass single‐bit modulators, the implications of these different alternatives are then presented in an incremental way.

Section 2.1 is dedicated to the second‐order modulator. Higher‐order single‐loop architectures are considered in Section 2.2, taking into account issues related to their practical implementation and problems not addressed by linear models, such as instabilities. Cascade topologies are covered in Section 2.3. In Section 2.4, the topological ...