I'm designing a PCB with a transceiver that has differential signal pins for rf. These differential signals travel to a balun, which transforms them into a single-ended signal (50-Ohm characteristic). This output goes to a on-board chip antenna, with a matching network at the interface between the 50-Ohm microstrip and the antenna.
Say that I have an arbitrary distance from the IC to the antenna. I can:
- Put the balun close to the IC, minimizing the length of the differential traces and having a longer single-ended trace, like so:
- Place it close to the antenna, running most of the signal path through the differential traces:
- (put it somewhere in between)
Which method is preferred? There are multiple transceivers on this board, and I suspect the differential traces radiate less. Is this true? Are there other considerations?