I have a doubt about how to use the baluns. I have seen in aplication notes that, in the evaluation boards, if you have a SMA conector (like an input or output to the PCB) it's used the balun to convert the unbalanced input (ANNTENA) to a balanced input (a differential input in a CI).
My question is: ¿Can I use a balun, inside the PCB, to convert the unbalanced output of an IC in a balanced signal (that is the input of the next IC in the chain)?
if I want to connect the output of the ADL5373 (I/Q Modulator) with the ADL5330 (VGA), I will have to convert from un-balanced to balanced. ¿Is a good idea to do that? If you see the document AN-826 the describe in the Figure 15 to connect the single-ended output with the low pin of the differential input, INLO (with ac-coupling) and the INHI (with ac-coupling too) to the ground. ¿When can I use this kind of connection?¿Has it any problem?
Thank you in advance!
Balun is the common product to convert single-ended(un-balanced) signal to differential(balanced) signal or vice versa. Usually balanced differential driving give better performance at common-mode, even-order performance than single-ended driving and so differential driving is recommended in terms of performance. But single-ended driving allows simple interface and it would be OK as long as performance is acceptable. So either balanced driving with balun or single-ended(unbalanced) driving is OK for the ADL5373-ADL5330 interface as mentioned at Fig 33 of ADL5330 datasheet, AN-826.