A vertically integrated tool for automated design of ΣΔ modulators

We present a tool that starting from high-level specifications of switched-capacitor (SC) ΣΔ modulators calculates optimum specifications for their building blocks and then optimum sizes for the block schematics. At both design levels, optimization is performed using statistical techniques to enable global design and innovative heuristics for increased computer efficiency as compared with conventional statistical optimization. The tool uses an equation-based approach at the modulator level, a simulation-based approach at the cell level, and incorporates an advanced ΣΔ behavioral simulator for monitoring and design space exploration. We include measurements taken from two silicon prototypes: (1) a 16 b @ 16 kHz output rate second-order ΣΔ modulator; and (2) a 17 b @ 40 kHz output rate fourth-order ΣΔ modulator. Both use SC fully differential circuits and were designed using the proposed tool and manufactured in a 1.2 μm CMOS double-metal double-poly technology.