GSM In-band spurious induced by flex PCB
I met a issue with ?Inband spurios around 500~700MHz wideband noise coming up. It's for sure is flex PCB that connect to main PCB make it instead any other radio module/PA/RF driver issue.
Could anybody giveme a guide how to trace it or if necessarily change is not allowable, like PCB layout, for current moent of the project, what can I else do for main PCB hardware design components.
Thanks a lot.
Regards,
Are you saying you are sending RF energy thru a flex PCB and it is generating spurs? Hmmmm.
I would look at the interconnect between the flex PCB and the hard PCB portions. Right at the interconnect, is there a good solder connection, some sort of adhesive connection, etc. Try experimenting with better soldering there.
Can you isolate the trace on the flex that is causing you problems? Try cutting up a few to isolate traces or groups of traces to see if you can isolate the problem connections.
The flex may be acting as an antenna, and causing a feedback loop. Depending on the signals that you have running on the flex, I'd try lo pass filtering the signals. You also may try making sure that the transmit path is well grounded in the 400-700 MHz range.
Dave
www.keystoneradio.com