Tutorials

These tutorials are a great way to get you introduced to the design flow of Couplings Designer. Note that you need additional software to simulate the physical electro-magnetic couplings used in the filter structures proposed. The documentation lists each feature of Couplings Designer along with tips on how to get the most out of this tool.
 
Advanced filter synthesis concepts

A demonstration of advanced filter synthesis concepts that can be applied to your future designs to meet the demand for stringent requirements. Couplings Designer makes it easy.

  • Transmission zeros – the importance of transmission zeros and how they can be engineered to create advanced filter responses for increased rejection and/or group delay equalisation.
  • Non-resonating Nodes, NRNs – the relatively new building block, a non-resonating node or NRN, can be used to create new advanced filter topologies.
  • Predistortion – the benefits of predistortion when size and cost requirements are stringent.
  • Resonator Q distribution – the importance of distributing the resonator Qs correctly when reducing the size of a filter implementation.
  • Topologies – the concerns involved in choosing an appropriate topology, especially the sensitivity issues inherited in certain topologies.
  • Optimization – the power of combining two synthesis methods, exact approximation with prescribed zeros and optimization, to synthesize a coupling matrix according to a specification.

 
Filter realizations

How to turn your synthesized coupling matrices into physical filters. Discover the benefits and versatility of coupled filter design with coupling matrix techniques; the independence on technology, frequency, bandwidth and port impedance.

  • Lumped filter design using coupling matrix techniques – Learn how to turn your synthesized coupling matrix into lumped elements for low frequency applications where waveguide and planar implementations wouldn’t make sense. It is also interesting reading for those doing miniature filters on thin film or MMIC at higher frequencies.
  • Combline cavity filter – In this tutorial we will learn how to synthesize and implement a chebyshev response with a combline cavity topology using Couplings Designer. Couplings are extracted and linked to physical dimensions and then combined to realize the final filter layout. It will be shown that unintended couplings may distort the passband and stopband performance. These coupling are analyzed by Couplings Designer with a new coupling matrix that takes them into account and the final physical dimensions are tuned to reflect the change, finally retreiving the chebyshev response.
  • Coaxial cavity filter with transmission zeros – An aluminum coaxial re-entrant resonator is designed for high Q to meet specifications on insertion loss. High rejection is achieved with a symmetrical pair of transmission zeros implemented using an electric probe. The filter is implemented with the well known folded topology which is fairly insensitive to manufacturing tolerances. Port tuning is introduced which cuts simulation time and makes the connection to the synthesized coupling matrix transparent.
  • COMING SOON – TE101 cavity-resonator filter
  • COMING SOON – Dual-mode microstrip open-loop filter with NRNs
  • COMING SOON – TM120/TM210 dual-mode cavity-resonator filter with NRNs
  • COMING SOON – Coaxial cavity diplexer with extended box topology
  • COMING SOON – Coaxial canonical (N zeros) inline filter with NRNs
  • COMING SOON – Microstrip dual-band filter with NRNs

 
Please leave a comment if you run into problems, have a feature request or if you find these tutorials helpful, all user feedback is welcome!

19 Responses to Tutorials

  1. Scott says:

    Nice work!!! It’s wonderful…

  2. Ed Rosen says:

    Have you advanced to a Total Mac version yet? I can’t seem to be able to open the Lite version on my iPad. Any thoughts on what my problem could be? Also, does the program include a Smith chart output ?

  3. Khawar says:

    Hi Goran,

    Can you please update on Dual mode cavity filter. I am designing a TM dual mode Cross shaped ceramic resonator inside a rectangular cavity and would love to get your tutorial on couplings between the two orthogonal modes and how to control and alter them.

    Best Regards,

    Khawar

    • Hi Khawar,

      I will write more tutorials highlighting dual-mode filters in the future. It is however hard to tailor a tutorial to a specific topology like in your case. Your cross-shaped resonator sounds interesting, is there any benefit of using such a resonator (spurious performance perhaps..) ? It all depends on your topology, how you excite the modes in your input/output coupling etc. however to find the coupling is essentially the same procedure as was done in the coax or combline tutorial. The difference is that you need a structure (tuning screw etc.) to create a perturbation for the resonating modes to couple to each other depending on the amount of coupling required.

      1. run an eigen mode simulation on your resonator and identify the modes (will have equal resonant frequencies)
      2. introduce a perturbation and run your eigen mode simulation and observe the resonant frequencies of these modes
      3. calculate the coupling factor using the formula in the combline tutorial from the lower and upper resonant frequencies (mode split)

      the perturbation can be introduced as a tuning screw located between the two orthogonal mode planes.. hope this helped you get started? you may share field plots of your structure and modes with me and I might help.

      Kind regards,
      Göran

      • Khawar says:

        Hi Goran,

        Thanks for the reply. I have modelled the test cavity and resonator as a circuit model in ADS and now getting the hang of things. As a learning process, I created a 20 MHz bandpass filter in HFSS and its equivalent circuit model in ADS. But the real task now is to study the two modes i.e. dual modes separated by 30 MHz coupling bandwidth. I actually want to specify the resonator such that If i get a certain puck, i put in my test cavity. measure the result and make conclusion that either the input/output coupling is wrong or the thickness or width is not right or the perturbation(diagonal cut in the cross for mutual coupling) is the problem. I hope i made myself clear to you. I also need to design a matlab code i.e to model the same L, C and input output coupling values to generate either the filter response or the dual mode resonator response!!

        If i can have your email, I would love to share my results with you.

        Best Regards,

        Khawar

        • Dear Khawar,
          I will try to respond to your message shortly. I have a lot of things going on the following days so bear with me. In the meanwhile you may email me at goran@versatilemw.com and clarify the resonator configuration you are using. Where is the diagonal cut made? Is it a perturbation cut in each edge of the cross resonator? I’ve never studied such a structure but wouldn’t a cross give you a quad mode resonator? You are talking about dual modes..

          Regards,
          Göran

          • Khawar says:

            Hi Goran,

            Thanks for the reply. I have emailed you my current research results. Hopefully it will give you a better idea of what i am trying to achieve. Waiting to hear back from you.

            Best Regards,

            Khawar

  4. Gil says:

    Hi Goran.

    I’ve tried to watch a few of your tutorials on a MacBook Pro laptop and I don’t see any speaker icons in the lower task bar nor do I hear any audio, which I suspect you did add. Any idea why this doesn’t work? Is it a flash player incompatibility thing by chance? Just curious…

    Gil.

  5. Doug says:

    Hi Goran,

    Nice app! Are you planning to update it for ios 7? It seems a little buggy. The older ios on my ipad works great but my phone with ios7 has some bugs in it. Mostly scrolling interfaces. Also, any plans for more features?

    • Hi and thanks for commenting,
      I will update it soon to work well with the new iOS interface. Also correct some minor bugs etc. I have some features planned. Anything special you would like to see that you are missing?

      Regards,
      Göran

      • Nam says:

        Thanks for the reply Goran. There’s a few things I that would be great to have and are as follow:

        1)a feature that would allow you to set the bounce-back/side-lope/transmission zeros to a specific height.
        2)add more than 2 markers that allow you to enter in the frequency of your interest.
        3)be able to tune multiple couplings so you don’t need to switch back and forward between the response and the M-matrix.
        4)be able to enter the frequency bandwidth instead of a percentage.
        5)(Optional) export optimized parameter with error and margin data.

        I’m pretty sure you’re busy but it would be nice to have those options. Overall, this is the best app I’ve seen. Great work!

        regards,

        Doug

        • Thanks Doug,

          great input, I will definitely try to think of how these features could be implemented in an intuitive and tap-friendly way in the iOS interface.

          1)a feature that would allow you to set the bounce-back/side-lope/transmission zeros to a specific height.

          thinking of adding an optimize option in the general chebyshev seed window that would allow the software to automatically determine the position of your zeros to best match your specification (goals). Requires quite a lot of work tho. This can be done in the current version by adding the number of zeros in the seed you want and then optimize the matrix afterwards.

          2)add more than 2 markers that allow you to enter in the frequency of your interest.

          the problem is that there are not that many pixels available for displaying multiple markers, will think of how to do it, any ideas?

          3)be able to tune multiple couplings so you don’t need to switch back and forward between the response and the M-matrix.

          perhaps quick access to recently selected couplings (say the previous 5 selected from the matrix)?

          4)be able to enter the frequency bandwidth instead of a percentage.

          this is definitely coming, changing center frequency/percentage to user entered band edge frequencies instead

          5)(Optional) export optimized parameter with error and margin data.

          the matrix can be exported as of now, the error of the filter response (compared to your specification) is visible in the goals tab. You want to export these values? what do you mean by margin data?

          Keep in touch and thanks again!

          Regards,
          Goran

          • Doug says:

            Hi Goran,
            1)thinking of adding an optimize option in the general chebyshev seed window that would allow the software to automatically determine the position of your zeros to best match your specification (goals). Requires quite a lot of work tho. This can be done in the current version by adding the number of zeros in the seed you want and then optimize the matrix afterwards.

            Your optimization is fast and awesome. I saw some program that was able to instantly set the bounce-back to the desire level so I just wanted to throw the idea out there.

            2) the problem is that there are not that many pixels available for displaying multiple markers, will think of how to do it, any ideas?

            Can you have a second marker option where you show only the loss where you have the marker data(below the graph) right now? I see that by removing the frequency, delta, and S11(which is always 0dB when looking at rejection) you can have at least 9 markers there. When you add makers, a different window pops up with drop-down menu allowing user to select either S11,S21, and a box that you can enter in the desire frequency. Then on the graph, have arrows pointing to where it is and the marker number. Below the graph(where you have the frequency, delta, and loss data), each line/row would display the marker number with the loss value. Although this is limited to 9 markers, but it is good enough to instantly view 2 markers for insertion loss, 2 for return loss and 4 for rejection. you can improve this further by adding another option for each marker with a drop-down menu to either enter a frequency point or a range. The range option will ask user to entering a specific frequency range(min and max). On the graph, you can display horizontal lines like you have for the optimization. The loss displayed at the bottom would be the worst case. What do you think?

            3)perhaps quick access to recently selected couplings (say the previous 5 selected from the matrix)?

            That would work!

            4)this is definitely coming, changing center frequency/percentage to user entered band edge frequencies instead

            That’s Awesome!

            5)the matrix can be exported as of now, the error of the filter response (compared to your specification) is visible in the goals tab. You want to export these values? what do you mean by margin data?

            I was think margin in terms of frequency shift. say you want to determine how much room you have if there’s a +/-2MHz shift due to temperature fluctuation. Say you’re looking at the upper rejection. How far can you shift up(frequency) before you lose that rejection. It would be nice to export them but I don’t think it’s necessary. Just some random idea that I thought would be nice to see on your app, but I can do this with the matrix you’ve provided.

            Thank you for your effort to improve this app, but do only what you think will work. After all, everything is done on a tiny iphone screen so there are limitations. Still, your app is the best I’ve seen. Keep up the great work!

            Regards,

            Doug

          • Dear Doug,

            thank you for your comments on how to improve the usability,

            2) it is by no means easy to implement markers in a sensible and intuitive way making it powerful. I agree with you that the user should be allowed to select what parameter the marker should indicate. Say you’re not interested in the return loss then displaying S11 is pointless. I will think of how to do it. If I redo it I want it to be general and not limited to a finite number of markers, either two easy to adjust ones as it is now or more general with unlimited number of markers and perhaps some some advanced features connected to them. Displaying them inline with the resonse as you mention might be a start.

            5) I usually design the response directly with the headroom required for tolerances and temperature but if you are constrained or want to analyze the filter for additional “what-ifs” I guess it might be a useful feature, perhaps some analysis button in the goals window could offer this in addition to being exported along with the matrix?

            also doing some work on making the general chebyshev seed window easier to use, instantly see what happens when changing order etc. and perhaps implementing a feature that will automatically suggest the parameters according to the specification

            thank you once again for your insight!

            Regards,
            Goran

  6. An says:

    Hi Sir/ Madam.
    i want to tuning coupling screw , I simulation in ADS and i have value of coupling capacitor.But I don’t know how to adjust length of Coupling Screw to achieve this result. Could you help me explain it or the way to translate value of coupling capacitor to length of coupling screw.

    Thank.

    An

    • Hi An,
      I assume you want to model your filter in ADS to do what’s called port-tuning, am I right? It is nearly impossible to have an accurate mathematical description of your coupling structure that relates to a capacitor. What you will have to do If you have an EM model of the filter is to simulate the s-parameters. Adjust the screw length and in ADS adjust your cap until it matches the EM response. That way you can create a table of lengths VS cap values and from there you can make a line regression to get a pretty descent mathematical relation. You can do the same in the lab by measuring your filter and adjusting the tuning screw.

      Hope it answers your question, you can email me directly if you need help how to set this up. I check my emails regularly!

      Kind regards,
      Göran

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