Computer-aided design (CAD)

Updated April 7, 2008

In all types of electrical engineering, the term "CAD" is rapidly being replaced with "EDA", which stands for "electronic design automation". We're going to stick with "CAD" since it's faster to say (and time is money, comprendez?), and everyone knows what it means, including the politically incorrect double-entendre in the Rhett Butler sense (which is no-doubt why the feminized software industry has switched to "EDA"!) But let's stop digressing... again...

In the future our chapter on CAD is (hopefully) going to include a lot more technical support, and will eventually be split onto many pages with examples of what to do and what not to do. Want to help? contact us! Attention EDA vendors - please consider renting some space here and providing some in-line content that will impress our readers and get you a good click-through rate! It's short money!

Being primarily "hardware guys" at Microwaves101, we try not to refer to software as tools. Software is software, you use it while sitting your increasingly fat butt in a chair. Tools are those things that real men (and men-like women) use in the garage or around the house, while skinning knuckles and getting grease on their pants. Hey, that was a seriously incorrect statement, oops, there goes another potential sponsor...

A clickable index to the slowly growing Microwaves101 CAD web resource:

History of microwave software (separate page)

Linear analysis software (separate page)

Synthesis, analysis and optimization

Optimization (separate page, new for April 2007!)

Netlist versus schematic capture interface

Physical versus ideal elements

Linear versus nonlinear analysis

Time domain versus frequency domain

Electromagnetic analysis software (separate page)

Computational electromagnetics (separate page)

EM analysis using Sonnet (separate page sponsored by Sonnet)

Layout software (separate page)

Laying out thin-film networks

Laying out printed wiring boards

Free printed circuit board software!

Laying out MMICs

CAD computer files: common file extensions

Software for coplanar-waveguide designs

Filter design software

Large-signal analysis software

Computer files: common file extensions you might see in microwave CAD

.gbr = Gerber layout file

.iff = intermediate file format

.s2p = S-parameter, 2-port, .s3p = S-parameter, 3-port, etc. Originally from Touchstone.

.ckt = circuit file (Eagleware)

.dwg = AutoCAD drawing file

.dxf = drawing interchange format

.gds = generalized data stream

Software for coplanar-waveguide designs

Many companies out there offer software that works in conjunction with the linear optimizers that are offered by the big four. An example is Coplan. This is a German company, and they are specialists in coplanar-waveguide design. Did we mention that the CPW elements in Microwave Office, ADS, Genesis and Ansoft pretty much suck? For microstrip there are scores of elements such as tees, miters, steps, etc., due to years of research in solving accurate and scalable closed-form expressions for the behaviors of these. But CPW has not been analyzed as fully as microstrip. Coplan uses a "field solver" to quickly generate the response of various CPW elements. If you plan on using CPW, plan on Coplan!

Filter design software

There are a large number of vendors selling filter design software these days, check the ads in any microwave trade journal. Our favorites (for the moment) are Eagleware's FILTER (lumped element filters) M/FILTER (microstrip filters), since it has a seamless interface to the Genesis linear design tool. You can download a fair amount of filter design software on the web for free, nerds have been writing their own filter code for as long as there have been computers. Heck, even Microwaves101 offers a free download for lumped filter design!

Large-signal analysis software

Coming soon!