MIDAS: Mixed Digital/Analog Sampled-Data Simulator

Faculty: Bruce Wooley
Students: Xinying Ding

Contents: Overview - News - Getting MIDAS - New Models - Bug Reports - Reference

Overview

MIDAS is a functional simulator for sampled-data digital and analog systems. Its purpose is to close the gap between an idea for an algorithm and a circuit implementation of that algorithm. Accepting a high level functional description of a system, MIDAS frees the designer from circuit details and yet provides the flexibility to include as many circuit limitations as desired. Fundamental relationships between subsystem parameters, such as the dynamic range or bandwidth of an amplifier, and the performance of the system can quickly be examined for a variety of possible architectures. Systems with multiple sampling intervals and nonuniform sampling are supported.

Other features of MIDAS include its computation speed, which is considerably higher than that of a circuit simulator, and the availability of pre-defined models for several system building blocks. The standard models provided with MIDAS include a wide variety of linear and nonlinear system elements, as well as models for generating test signals, such as sinusoids or Gaussian noise. Several different analysis techniques are available to examine internal and external signals of the simulated system. These include transient analysis, spectral analysis, distortion analysis, and the estimation of statistical quantities such as mean, power, and probability density.

MIDAS provides two interfaces for the user. The configuration and parameters of the simulated system and the analyses to be performed are entered by means of an input file that builds on models for primitive functions such as adders, quantizers, delay elements, sinusoidal or other sources, and signal analyzers. These models can either be the standard models included with MIDAS, or user-defined models. The second user interface is the capability to add new models to MIDAS. New models are compiled directly into the main program, making their execution very fast. This also makes it easy to incorporate existing code, from program libraries for example, into new models.

News

The new version of MIDAS, version 3.1 is now officially released! The most important enhancement in the new version of MIDAS is the addition of an integer data type. Integers are useful in simulating digital systems. For example, the effects of truncation and overflow can be readily evaluated in a digital noise-shaper when using integer net signals in conjunction with models that operate on them.

The MIDAS 3.1 distribution also includes 86 new models and 20 new example input files. The manual has been expanded and includes several relatively elaborate examples to help users become familiar with the capabilities of the simulator quickly.

The file inclusion feature via the include command has been enhanced so that it can utilize the standard UNIX file expansion character, ~. Finally, the output of MIDAS 3.1 is along stdout as well as stderr to make it easier to separate the netlist echo and error messages from the simulation results.

How can I get a copy of MIDAS?

To setup MIDAS at your site you will need

The MIDAS source code, which comes with the manual and many demonstration netlists
A C++ complier (version 3 of the language), standard tools to unpack the code (uudecode, tar, compress), and the make utility
A graphing tool, such as iplot, xmgr, or xgraph, to view the output in graphical form

To get a copy of the MIDAS v3.1 distribution, send an email request to professor Wooley (wooley@par.Stanford.edu) along with your association and a brief project description (how MIDAS will be used) for our tracking purpose.

To get a copy of just the MIDAS v3.1 manual as a compressed file, click here ( pdf or ps ).

To get a copy of xgraph v11 as a compressed tar file, click here.

For a list of public FTP sites for the GNU C++ compiler, as well as various public domain graphing tools, click here.

C++ is available without charge from the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307 (telephone 617-542-5942, Email gnu@prep.ai.mit.edu). C++ is also available from other vendors including AT&T, Software Sales and Marketing, P.O. Box 25000, Greensboro, NC 27420 (telephone 800-828-UNIX).

Look here for new models!

As we come up with interesting new models, we will make them available to the MIDAS user community by placing them here. Check here periodically for cool new models.

If you have a model that you would like to contribute, please email it and a short description to Xinying Ding,

To see new/modified models created in the time period 10/8/97 to 10/15/97, click here.

Comments, suggestions, bug reports

If you have any comments, suggestions, or bug reports please send an email to Xinying Ding,

Reference

This is not the latest version of MIDAS but is a good introduction

Louis A. Williams and Bruce A. Wooley, "MIDAS - a functional simulator for mixed digital and analog sampled data systems," IEEE International Symposium on Circuits and Systems, vol. 5 of 6, pp. 2148-51, 1992.