Hello Stefan

Now that Qucs 0.0.10 has been released I am trying to plan my future work on Qucs digital simulation and analogue modelling.  The last few months have seen Qucs progress at a very fast pace allowing the package to mature to such an extent  that it is now possible to use the software for real design work.  Much work still remains to be done in both digital simulation and analogue component modelling - both of these are where I feel I can contribute a useful input to the project.
The following notes present a rough outline of the topics I propose to work on over the next few months.  I have also posted a copy of this note to the Qucs development site so that other Qucs developers/users can keep in contact with the developments I am proposing - I also hope that this will result in feedback from other Qucs users.

1. Digital simulation.

The second update to the "getting started with digital simulation" gives an insite into the way digital simulation is developing with Qucs/FreeHDL.  One of the next logic steps forward is to develop libraries of digital components - this involves the use of VHDL packages, VHDL text files and libraries of digital component schematics (that are functional of course).  Recently I have tested VHDL packages using Qucs/FreeHDL and find that they work ok.  The next stage is to start writing VHDL libraries of components which can then be included with future releases of Qucs/VHDL.   At the moment individual digital component schematics are limited to connections of type bit.  In the longer term work needs to be done on improving the Qucs digital GUI to include both bit and std_logic bus structures - this however, is more in the domain of Gopala than mine.  I also propose to write a digital component specification booklet that presents the details of each component, this will be in a similar format to the Measurements Expressions Reference Manual written by Gunther.

2. Analogue component modelling.
Work on the new 555 timer model is now complete and I will start writing a tutorial article for posting to the Qucs site in the next few days.  A range of 555 models will also be made available at the time the article is published.  I also propose to update the Operational Amplifier tutorial to include models for power supply rejection effects in general purpose OP AMP models.  Longer term the analogue modelling effort needs extensions to Qucs that include subcircuit   parameter passing, component values defined by equations and non-linear controlled sources.  These I now are already on your to do list.  Once in place it will then be possible to develop general purpose models for a wide range of analogue components, significantly extending the types of circuit that Qucs can simulate.

The ideas listed above will probably take most of my spare time over the next few months.
Your comments, and indeed other comments from other developers and users, will be most welcome.


Mike Brinson


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