Design of Wideband balun

Hi

I would like to design a wideband balun (1-3GHz)... in HFSS...

Does anyone has any suggestions which topology to use?

Does anyone has a tutorial about designing balun in HFSS?

I found a paper on designing a wideband balun. The paper is "A 6 to 20 GHz Planar balun using a wilkinson divider and lange couplers", by J. Rogers, R. Bhatia.
I am not sure, this is what you are asking?

-sv

Hi saadpaul,
I worked in the design of a planar wideband balun with the characteristics that you mentioned.
You can start with the ideas of "A Wideband Balun — How Does it Work?", by Thaysen, and then the design can be improved using FEM simulations. I did it and reached a 0 - 3,5 GHz balun with a |S11|< -10 dB.
Hope it helps

Hi paujuan,

Even I designed a wideband balun, and used Lange couplers at the outputs to achieve 180 phase difference. Did you also use Lange Couplers?

-sv

Dear,
The use of Lange couplers seems a good choice for a certain range of frequencies, but I am not used to its usage, since its performance for low frequencies does not seem really optimum.
Do you suggest to use them under 1 GHz? The Thaysen balun has a reasonable good response from DC to 3 GHz, but I would really like to know if your option is useful for that band too.

Lange Couplers are used for achieving wide-band characteristics (The paper is "A 6 to 20 GHz Planar balun using a wilkinson divider and lange couplers", by J. Rogers, R. Bhatia). Because, transmission lines with an electrical length of 180 degrees across one of the outputs to achieve a 180 phase difference provide only 20% bandwidth. But designing with Lange Couplers is difficult, because the width and spacing of the conductors are less than 0.1 mm to achieve a good performance and you need bond wire connections as well.

Thaysen's paper used radial slots to achieve wide bandwidth (0 to 3 GHz), I have never worked with radial slots. I think it is better to go with radial slots, because the dimensions are some what achievable. Whether you design with Lange Couplers or radial slots (Thaysen's paper) you cannot avoid bond wire connections.
So go with the Thaysen's paper.

-sv