first-time-right in rf/microwave cad software

[kleinesmurf69]

hello,

these days quite some rf/microwave CAD software (ADS, microwave office, aplac...) manufacturers claim there products enable you to design first-time-right. is this possible as they claim or is this pure marketing strategy? I have the feeling lots of the models in this software are inaccurate. for instance: smd inductors come in different technologies and thus should have different models, do they?. iI would like to have some discussion about this topic before investing in some expensive software. the design process now involves some out-to-date software and at the end I am still spending a lot of time debugging and tuning manually. if the first-time-right statement is true, or close to true, my design time would be reduced to 50% of my current design time in some cases and this justifies an investment in an expensive tool.

thanks.

best regards.

 

[flatulent]

These programs are no better than the component models. If you use discrete parts from manufacturers with no or poor models you will still have problems, but fewer of them.

Even low cost modern programs can be good. One of my friends uses a ten year old version of Eagleware Genesys and the transmission line filters work exactly as synthesized and simulated on it.

 

[flyhigh]

Hi,

I agree with Fatulent. Garbage in, garbage out, this is the old true. The simulation tools are great but the models of acctual passives and active devices that we have to use are sometimes more poetic than accurate. However, once you have the right models, (meaning both, fitted to describe actual device and suitable to be implemented in particular simulator) you can get excellent agreement between simulated and measured. Then any simulator will do.

In my company we have people dedicated to modeling. Before this was the case, I did designs, both, linear and nonlinear, with Ansoft Serenade 8.0. The Ansoft proprietary model for the device I was using was very good and, of course, it matched up very well with simulator requirement. Agreement between simulated and measured was 100%!

flyhigh

 

[djalli]

flyhigh of course every company has people in modeling.

You need to make models. Nobody will be buying from you if they do not see you do not have models for simulations even if you say your calculations are right.

 

[DJ]

I agree. Modeling is one of the most important step (we have a group) in designing complicated circuits such as MMIC.
ATC as well as Dielectric labs supply the capacitor models or S parameters, but never trust. If your design is based on several componnents it is better to test them before.
I use to call all softwares as Matrices multiplication and no more. It should be mathemtically accurate calculation but the real question is: Do you trust the active device model? Do you know the MIM capacitor model and its tollerance? and the same question for all other library componnents.

 

[flyhigh]

flyhigh of course every company has people in modeling.

Well, I don't think so! There are a lot of companies doing models for the other and most of the small companies are using manufacturer's or other publicly available models. Modeling requires highly specialized and titled personel and very expencive equipment, it can't be afforded in every company!

I am lucky to work for one large company, obviously djaly you share my luck too. I used to work for a small company where we had to rely on work of the others. The outcome was not always succesful!

flyhigh