wide band matching with transmission line ?

[Ata_sa16]

Hi people,

I want to study about wide band matching using transmission line. Can anybody provide me with a source ?

It can be ADS tutorial or an written example ?

For example I want to know how this one is designed (NOT lumped elements part, T-Line design part).

 

[FvM]

The transmission line stub design looks like an emulation of lumped elements, it's probably not designed using specific design methods.

Both "wide band" matching circuits are approximations, you need to know the frequency range and acceptable impedance ripple to decide about required number of elements.

Did you check the actual impedance curve implemented by the circuits? It's not mind blowing, I presume.

 

[Ata_sa16]

There is no information about how it is designed. Its easy to design wide band matching with lumped elemets using ADS and i know how to design single frequency matching network with Tlines as well. But this one is so tough!!!!

 

[FvM]

You are most likely overrating the "wide band" performance of the matching networks. Do you know any specification?

The transmission line are operated in a L < 0.1λ range as far as I see, behaving as lumped elements.

 

[ferdem]

Cascaded quarter wavelength transformers can be used to have wideband matching. A single transformer matches at a single frequency, however, by cascading multiple transformers with properly adjusted impedances you can achieve wideband matching.

 

[Ata_sa16]

Thank you for help I exactly know what is this for. My question is how ? design steps ? what is the method ?

 

[volker@muehlhaus]

I think you are looking for this conversion:
https://www.rfcafe.com/references/electrical/lumped-distributed-components.htm

 

[Ata_sa16]

I found this before but it does not help

 

[maktoomi]

Ata, this circuit topology is from Dr Andrie Grebennikove famous "Switch Mode RF and power amplifiers" book. I have bought my own copy. But, if you visit his researchgate profile page, he has shared PDF version of many of his books. Download them from there. Meanwhile, I have snipped the explanation given in the book (page 286, 2nd edition):



The idea is to fisrt make a low pass prototype and replace lumped components with transmission lines (and of course you need to otpimize a bit). How do you design a lumped element network? Well, it is based on Tables given in the following paper:

G. L. Matthaei "Tables of Chebyshev impedance-transformation networks of low-pass filter form" Proc. IEEE, vol. 52 no. 8 pp. 939-963, 1964.

You can also refer to Dr Andrie's "RF and Microwave Transmitter design" book, where he talks about designing wideband matching.

When the load and source impedance are real as in the above case, designing such network is not that diffcult. But, when either of the impedances become complex and frequency dependednt, it becomes tough to design wideband matching network.

For example, see a transmission-line technique discussed in:
K. Chen and D. Peroulis, "Design of Highly Efficient Broadband Class-E Power Amplifier Using Synthesized Low-Pass Matching Networks," in IEEE Transactions on Microwave Theory and Techniques, vol. 59, no. 12, pp. 3162-3173, Dec. 2011 : https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1927&context=nanopub

Also, keep in mind what FvM said

"Both "wide band" matching circuits are approximations, you need to know the frequency range and acceptable impedance ripple to decide about required number of elements." There is no perfect match in wideband network. This brings me to mention Real-Frequency techniques that gives you lumped element based network. Then, perhaps you can transform them using techniques discussed in Dr Andrie's book.

I am not in Industry, I think those guys could tell you more practical ways of doing that. I guess, they would be using routine found in comercial softwares such as ADS/Genesys to automate the design of matching networks.


Regards

Maktoomi.