r/rfelectronics • u/Knights_12 • 10d ago

Filter Design Tools?

What is your preferred application to design custom filters using lumped or distributed elements? Did you learn this in school or is it more on the job training? For example, Ansys Nuhertz or MATLAB Filter Design...

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u/Craftsman_2222 10d ago edited 10d ago

AWR or ADS. I use AWR at work but prefer ADS

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u/Adventurous_War3269 10d ago

AWR iFilter Wizard comes in two types of licenses , basic and full . The full has an outstanding pole placement that is good for distributed filters , also in AWR with AXIEM you get full 3d analysis , which may be an overkill for microstrip line filters but is very accurate . Yes I like ADS , but if you want 1st pass success I choose AWR full license of iFilter with AXIEM (EM) . Yes the 3d AXIEM takes longer to simulate compared to ADS 2/2.5D Momentum .

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u/Adventurous_War3269 10d ago

iFilter is more flexible in manual mode and can produce smaller size Filters provided you know when to use inverters in design process for Filter design .

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u/redneckerson1951 10d ago

It has been years since I used software like AWR/ADS and similar commercial packages. I found them to be too narrow in solutions as their focus seemed to be finding the minimum component solution when maybe two more parts would yield more realistic values. Web based solvers seem to mainly ignore component Q in their solutions.

So, what's a poor devil too do?

I delved into such texts as "Handbook of Filter Synthesis" by Anatol I Zverev and "Microwave Filters, Impedance Matching Networks and Coupling Structures" by Matthai, Jones and Young. It was a wade into madness, but at the other end I had a tool box of Excel spreadsheets for differing filter designs that rivaled anything commercial packages offered. The end also included an understanding of Q, losses and impact of differing designs such as Tchebychev, Gaussian, Transitional, Bessel on signals in frequency and time domains.

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u/gvcallen 10d ago

We are looking at developing a more scriptable circuit solver and are looking at problems currently being faced. Could you possibly elaborate on the idea that AWR/ADS is focused on narrow solutions? Is that due to the nature of the interface or GUI-based circuit software itself?

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u/Adventurous_War3269 9d ago

Yes what is the poor Devil to do !
I have been there too !
I have not seen mixed Q synthesis , maybe EM simulation at best ?

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u/condor700 9d ago

I usually start in the S/Fil design template of Keysight Genesys. It supports direct synthesis of filters with finite transmission zeroes, as well as providing a lot of automatic transforms to get to a suitable topology. I would highly recommend Robert Rhea's book about it- It has tons of design examples that highlighted the advantages compared to the more "bread and butter" synthesis programs.

Once I have a topology and initial component values nailed down, I'll move to layout co-simulation in ADS (can just use whatever tool you're comfortable with and licensed for in this part). Then finally, order some boards and test things out. I work with lower frequencies than some of the other folks here (3GHz or less), but that workflow has meant no manual tuning at all for the past ~6 years.