Mixed Signal Engineering

Mixed Signal circuits consist of at least one analog and one digital part. Each on it's own can be a rather tricky task, but together they bury caveats for the unweary. Both parts interact not only at their defined interface points but at many others, too. Engineers try to tackle that problem by extensive simulation, but simulation can be only as good as the models and methods are. Detailed models and thorough methods are preferable, but they drive up the time for a simulation run. So most of the time simpler models and methods are used to get the job done in time, bringing in the risk of missing important side effects.

The best way is to design a mixed signal device in such a way that it is doing what it is supposed to and only this - the approach of "guaranteed by design". Although this makes the task much more demanding it is the only way to be sure that the product will perform as intended and without any quirks. Simulation can then be used to verify the correctness of the approach and can be run with the best methodes and exactest models, because it is run only once (if the design is really flawless) or at least only a few times. Here are some ground rules to give you a starting point:

© Paul Elektronik, 1998-2002