Online Tool for Rapid Continuous-Time ΣΔ Modulator Design

ΣΔ A/D converters are the state of the art for many different applications. The basis for this type of A/D converter is the ΣΔ modulator. For a long time, discrete-time (DT) ΣΔ modulators dominated as their design techniques could easily be adopted to ensured high performance.
In  the  recent  time  continuous-time  (CT)  ΣΔ  modulators  have  gained  more  and  more  popularity because of its high speed and inherent signal filtering capabilities. The established design process for  these  modulators  consists  of  the  calculation  of  a  DT  ΣΔ  modulator  and  a  subsequent transformation into a CT ΣΔ modulator or the reuse of prior loop-filter topologies. This process is highly dependent upon the knowledge and experience of the designer.

In this project, a design tool is developed that allows the direct design in the continuous-time domain. It relies on a heuristic search that is based on a genetic algorithm. To achieve very short response times in the range of seconds for a complete optimization, the algorithms are implemented on a GPU to allow a heavily parallelized execution of the simulations. Moreover, the tool includes several non-idealities to calculate more than just a rough estimation. No further sophisticated knowledge on loop-filters, modelling and transformations is needed.

The web-based GUI for this design tool is available under

Due to the demand of more sophisticated architectures and modulator types, the scope of the toolbox steadily increases. Therefore, it is the main objective of this project to develop in the next step the capabilities to simulate and optimize CT ΣΔ bandpass modulators and expand it to more types in the future. Further, the flexibility of the underlying models and the effectiveness of the optimization algorithm are increased steadily to extend the field of application.

Figure - Online Tool for Rapid Continuous-Time SD Modulator Design
Figure - Online Tool for Rapid Continuous-Time SD Modulator Design

Project member

M.Sc. P. Kässer
Dr.-Ing. J. Wagner