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

Today's trends in mixed analog-digital circuit design show that oversa mpling techniques will probably be preferred over traditional approach es for implementing high-resolution data converters. Two main factors have limited their widespread use: common analytical as simulation too ls are inadequate for exact analysis because these circuits are inhere ntly nonlinear, and conventional electrical simulators are not suitabl e 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 dra wbacks. The simulator is behavioral, general purpose and fully user-fr iendly. Because a set of basic building blocks is available, generic s witched-capacitor noise-shaping A/D converters can be analyzed simply by building a netlist file. Two hierarchial levels have been considere d for circuit description: block-level for sub-circuits like quantizer s and digital filters, and component-level for sub-circuits like the i ntegrators where switches, capacitors and operational amplifiers are u sed 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 cir cuits. The program is written in C language, uses dynamic memory alloc ation and is very fast.