One bit higher order sigma-delta A/D converters

A topology for higher-order sigma-delta modulations is described, and synthesis equations are given which allow for the arbitrary shaping of the signal and quantization noise transfer functions. The synthesis procedure is similar to that of switched-capacitor filters and uses switched-capacitor design techniques such as dynamic-range scaling, impedance scaling, and circuit noise analysis. Placement of passband zeros for the optimization of the quantization noise transfer functions is discussed, and some results measured on a third-order test chip are presented. Simulated results on nonlinear stabilization of the loop are discussed. The need for simulating the analog front-end along with the digital filters to find the true dynamic range of the system is indicated