Ti 253x matching question

Hi guys
Can anyone explain the attched TI 253x matching network. The network matches balance output to a unbalnance antenna.
Thanks

It goes like this:

C251, C251 are DC block
L251 is used to compensate some internal cap, to have a real differential impedance
C252, L252, C262, L261 is the real balun; it gives a 90 deg phase shift on each branch (with opposite sign) plus a certain impedance transformation.
C253, C254, C255 probably a match to 50 Ohm plus some filtering

Hope it can help.

Mazz

What should be the value of the c252 and l252?
It looks to me the value of cap and inductor are not unique
It seems as long as omega=sort(1/Lc)
It seems it will work
Do I miss something here ?
Thanks

You are right, the cap and inductor are not unique. If you consider the ratio between single ended to balanced resistance, they become unique.

See here: https://www.edaboard.com/thread143361.html
and here: http://www.atmel.com/dyn/resources/p...ts/doc8113.pdf

Mazz

Hi, Mazz,

Your file doc8113.pdf has password, can you remove the password?

BR,
Tony Liu

Hi Tony

I'm not an Atmel engineer, no I can't.

Mazz