Quantizer Nonoverload Criteria in Sigma–Delta Modulators

A simple method to guarantee absolute stability in multibit sigma-delta modulators (SDMs) is to ensure that the quantizer never overloads. This applies to any SDM. Derivation of the requirements for nonoverload have previously been shown for different types of modulators; the sigma-delta or output-feedback modulator with rounding quantizer as well as the error-feedback modulator using truncation. Here, these nonoverload requirements will be clarified and a unified formulation is presented that is not limited with regard to modulator topology or quantizer function