Rene Harder wrote: > Yes [ R4401 ] looks pretty much like a current limiter.
Joerg and I had a quick discussion on IRC: - he agrees that R4401 is probably a current limiter to protect the codec's MIC1 input. Can't hurt to have it. - he also agrees that C4405 should go. Also, R4404 can safely meet the same fate. - he suggests to switch to a symmetrical configuration for the microphone, like in earlier GTA02 variants or in GTA01. The change to single-ended in GTA02v6 was an unsuccessful attempt to solve the buzz problem. A symmetrical design would have the advantage of better common-mode rejection. In the symmetrical design, R4301 and R4302 would be useless, so it's not any more complicated than the asymmetrical design. Plus, it would actually be a bit clearer what things do. Regarding component choices, I looked for filter arrays which would save even more space, e.g., Murata's NFA series. Alas, they all seem to be difficult to source. - Werner _______________________________________________ gta02-core mailing list [email protected] https://lists.openmoko.org/mailman/listinfo/gta02-core
