The AD8342 shows RF Spurious at the Output

Document created by analog-archivist Employee on Feb 23, 2016
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I am using the AD8342 with a balun at the Output like described in the
datasheet. We found RF spurious at the output - what could be the issue?
Now I experience a lot of unexplained problems, as strong spurious extending
well beyond intended
spectrum. Not surprisingly, the IC runs quite hot.


I finally found the Big problem plaguing our design; apart from the
exposed pad that should be connected to GND, we used a ceramic balun as output
“transformer” (reference 1600BL15B100), since our output frequency was fixed at
1575MHz; by the way, quite unexpectedly, the AD8342 was absolutely not
appreciating this component, causing wideband noise/instability.
Substituting with an ETC1-1-13 (with adequate polarization) just works as

In addition the exposed Pad should be connected to GND