How good is your launch into your test trace? If it has a large discontinuity
it may be masking the true impedance. Try looking at the trace with a TDR
display and see what the trace impedance is.
Tom Dagostino
Teraspeed LabsOn Dec 11, 2016 8:17 AM, sunil bharadwaz
<dmarc-noreply@xxxxxxxxxxxxx> wrote:
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Hello Group ,
We seem to be running into issues while getting PCB's fabricated with 50 ohm
lines.Our Freq band of interest is 2 Ghz to 6 Ghz.Tried checking these traces
on a VNA.The return loss looks decent @ 2 Ghz , but seldom looks good at 5Ghz
& above .
The fabricator does send test coupons & impedance reports @ TDR .This does
notcover the freq response .
This is not issue with any single fab . This seems to be a general problem ,
where return loss isnot flat across freq band .
Wanted to check if there are ways to tackle this issue .
Thanks much.
RegardsSunil.B
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