Where is balun needed in RF frontend designs?

[tsunghan]

About Balun

Hi
I am so confused about balun. Someone use it to complete RF frontend design and others not. What will happen if balun is lack ? When the balun is necessary and can not be neglected ? Thanks in advance.

 

[Element7k]

Re: About Balun

Hi,

balun basically for impedance transformation, matching so max power can be transferred. and depending on whether it can be practical. E.g. if requirement too wideband then balun not needed. If freq too low and not enough space, then other techniques are applied.

Cheers,
Element7k

Hi
I am so confused about balun. Someone use it to complete RF frontend design and others not. What will happen if balun is lack ? When the balun is necessary and can not be neglected ? Thanks in advance.

 

[BigBoss]

Re: About Balun

BalUn is a device to transfer the energy from Balanced-to-Unbalanced
(or vice-versa) configuration. Differential amplifiers , dipol antennas , mostly mixers etc use Balun.

For instance 50 Balanced input impedance can be converted 50 single ended Unbalanced input/output.

Additional to , it may serve a impedance matching function but it's not neccesary.

Principally, it serves balanced-unbalanced transforming between the devices.
There are many types of Balun such as L-C , Marchand, Transmission Line Balun, transformer with grounded seconder etc.

Unfortunately, there isn't so much book on this subject, only some papers and company app.reports.

A Balun can not be neglected if it's in a circuit.
Regards

 

[AL0117]

Re: About Balun

Hi,

I posted earlier the book of

J.Sevick :Transmission Line Transformers

**broken link removed**

Take a look in chapter 9 about the baluns.

regards, Al

 

[tsunghan]

Re: About Balun

Hi everyone

I have seen a paper about antenna and balun before. The author used balun in his leaky-wave antenna design. After that, the ground plane can be moved and the required length of this antenna also decreased. I am very interested in it and don't unstandard how it works. Does anyone have idea about it ?

 

[kayaoo]

Re: About Balun

i have a question:Why so many transceiver use balanced outputs while so few PA have a balanced inputs? Does balanced structrue brings benifits to transceiver IC design and unbenifits to PA design? Why not use a uniform interface? can someone explain it for me?

I have seen a paper about antenna and balun before. The author used balun in his leaky-wave antenna design. After that, the ground plane can be moved and the required length of this antenna also decreased. I am very interested in it and don't unstandard how it works. Does anyone have idea about it ?

really interesting. can u post it?