GSM-noise "buzz" issue / ways forward
andy at openmoko.com
Mon Sep 22 16:03:55 CEST 2008
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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
| 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
| 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,
| than probing on a setup that's completely changed by mere applying a
We even agree about the possibility to find a better rework too now,
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