up mixers which is used in GSM have 4 quadrature LO signals and 4 Baseband signals. I have met with several problems when I measure it.
1) how to input 4 LO signals? 1 LO to a balun, becoming two differential signals.
then use power spliter to get 0 degree and 90degree signals ---is it practical?
if not, how should I do?
2)If I want to get 4 baseband signals with a DC level,
can I use balun? (is there any balun that can transform one way ac signal to 2 way signals with DC level?)
thank you very much.