[gta02-core] ECN0019 (was Re: ECN0010: LDO2/LDO4 swap implemented)

[Werner Almesberger]

Rene Harder wrote:
> Rene Harder wrote:
> >> Joerg Reisenweber wrote:
> >>>   we should replace (A)-R4305-(B) by (A)-R4305-(X), (X)-C4306_NC-(GND),
> >>> (X)-R4399_0R-(B)
> >>>   move C4303, C4304, R4305 next to wm8753, behind B3005
> >>>     
> > I think that's a really good idea. In this configuration you completely
> > prevent RF from getting into MICBIAS through JK4401.
> >   
> I rewrote ECN0019 to reflect those changes and reopened it for further
> discussions.

Hmm, I think this is quite different from what Joerg had in mind.
Here's my attempt at making sense of it:
http://svn.openmoko.org/trunk/gta02-core/docs/ecn/ecn0019/swap.ps

Note that this drawing doesn't include ECN0042 or ECN0043.

Also, the description of how the the buzz fix works isn't quite
correct - it's not blocking RF noise coming from the microphone,
but it's filtering the (audio frequency) buzz already riding on
MICBIAS, originating from the jack.

- Werner