[gta02-core] ECN0019 (was Re: ECN0010: LDO2/LDO4 swap implemented)
werner at openmoko.org
Mon Nov 30 12:09:55 CET 2009
Rene Harder wrote:
> Apart from that, it's exactly what I had in mind,
Good, I guess it must have been C4307 that threw me off.
> except for relocating
> the choke. I would prefer to handle this in a different ECN,
Okay, makes sense.
> with moving C4301/2 and C4305 to the codec side of the choke.
I was wondering about them as well. Joerg said that having them
close to the microphone, before the choke, would be better, "to
give RF a path to GND, so actual HF voltage isn't that high".
I'm not sure this makes sense to me. So I simulated an LC and a
CL configuration . I found that they perform pretty much
identically when input and output impedance are high. They do
show a marked difference if the output impedance is very low,
and also a low input impedance causes some slight differences,
with L-at-input showing better performance.
More information about the gta02-core