A VERTICALLY INTEGRATED TOOL FOR AUTOMATED DESIGN OF SIGMA-DELTA MODULATORS

We present a tool that starting from high-level specifications of swit ched-capacitor (SC) Sigma Delta modulators calculates optimum specific ations for their building blocks and then optimum sizes for the block schematics, At both design levels, optimization is performed using sta tistical techniques to enable global design and innovative heuristics for increased computer efficiency as compared with conventional statis tical optimization, The tool uses an equation-based approach at the mo dulator level, a simulation-based approach at the cell level, and inco rporates an advanced Sigma Delta behavioral simulator for monitoring a nd design space exploration, We include measurements taken from two si licon prototypes: 1) a 16 b @ 16 kHz output rate second-order Sigma De lta modulator; and 2) a 17 b @ 40 kHz output rate fourth-order Sigma D elta modulator, Both use SC fully differential circuits and were desig ned using the proposed tool and manufactured in a 1.2 mu m CMOS double -metal double-poly technology.