GSM-noise "buzz" issue / ways forward

[Andy Green]

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Somebody in the thread at some point said:

|> What I don't understand is how we get from 1.7GHz "infestation", which
|> is clearly an issue since a bead on p4 of the headset jack does
|> something, to these LF "dents" on MICBIAS.

| My theory is RF is spoiling VREF, by entering the Wolfson chip via
arbitrary
| path (actual path doesn't matter, as RF can "jump" inside chip) and being
| rectified on some nonlinear component of the circuitry inside chip

You might remember I repeatedly proposed this ever since I found the
errors around Vmid and Vref caps, and keep noting I can make the buzz
come by scope probe on Vref.  Most recently, earlier today on this thread...

Still, it sounds encouraging we found something to agree about.

| Well maybe luckily we *might* eventually find a magic place for a
(33pF) C
| somewhere near Wolfson chip, to rework GTA02 out in the field this way.
| Anyway I'd rather expect this magic fix to be found by try and error,
rather
| than probing on a setup that's completely changed by mere applying a
probe to
| it.

We even agree about the possibility to find a better rework too now,
excellent.

- -Andy
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