Analyzing continuous-time ΔΣ Modulators with generic behavioral models

In a generic behavioral model of an analog or mixed-signal electronic system, the internal and external signals and their interactions are formulated by more general descriptions than in commonly used behavioral models. This allows a more flexible design methodology. Whereas a behavioral model models an architecture of a system at a specific abstraction level, a generic behavioral model is built up out of generic functions that by specialization of these functions allows the modeling of a wide range of system architectures with different degrees of modeling accuracy. This enhanced abstraction level makes the approach suited for systematic analysis through refinement and architectural exploration of analog and mixed-signal building blocks and systems using computer-aided-design tools. As an application of this methodology, a generic behavioral model has been developed for continuous-time (CT) ΔΣ analog-to-digital converters (ADCs) together with the specialization functions to take into account all major nonidealities at different levels of detail, including effects like jitter, saturation, and weakly nonlinear distortion. The results of experiments of a SystemC implementation of the model are presented. Compared to other models for analysis, the proposed method enables high accuracy even at low abstraction levels, whereas the event-driven character of the model results in short simulation times compared to time-marching simulations of behavioral models, written for example in very-high-speed-integrated-circuit (VHSIC) Hardware Description Language Analog and Mixed Signal (VHDL-AMS) or Matlab/Simulink. The flexibility of the model is demonstrated.