A Tool for automated design of sigma-delta modulators using statistical optimization

Abstract

A tool is presented which starting from high level specifications of SC σδ modulators (resolution, bandwidth and oversampling ratio) calculates first optimum specifications for the building blocks (op-amps, comparator, etc.), and then, optimum sizes for their schematics. At both design levels (high-level synthesis and cell dimensioning), optimization is performed via using statistical techniques and innovative heuristics, which allow global design (independent on the initial conditions) and increased computer efficiency as compared to conventional statistical optimization techniques. The tool has been conceived to be flexible at the high-level part(via the use of an architecture independent, behaviourable modeling approach) and completely open at the cell-design part. Performance of the tool is demonstrated via the automatic design of a 16bit-dynamic range, 8Khz second-order SC σδ modulator in 1.2 μm CMOS technology, for which measurements on a fabricated prototype are reported.