TOSCA - A SIMULATOR FOR SWITCHED-CAPACITOR NOISE-SHAPING A/D CONVERTERS

Today's trends in mixed analog-digital circuit design show that oversampling techniques will probably be preferred over traditional approaches for implementing high-resolution data converters. Two main factors have limited their widespread use: common analytical as simulation tools are inadequate for exact analysis because these circuits are inherently nonlinear, and conventional electrical simulators are not suitable for simulation because very long transient analyses are required. A software tool named TOSCA (Tool for Oversampled Switched-Capacitor A/D Converter Analysis) has been developed in order to overcome these drawbacks. The simulator is behavioral, general purpose and fully user-friendly. Because a set of basic building blocks is available, generic switched-capacitor noise-shaping A/D converters can be analyzed simply by building a netlist file. Two hierarchial levels have been considered for circuit description: block-level for sub-circuits like quantizers and digital filters, and component-level for sub-circuits like the integrators where switches, capacitors and operational amplifiers are used as building elements. The developed models allow the most relevant non-ideal parameters of the components to be taken into account and a set of post-processing facilities allow extensive analysis of the circuits. The program is written in C language, uses dynamic memory allocation and is very fast.