Yesterday, Joerg, Rene, and I discussed the GPS antenna input some more on IRC. The conclusion:
- Joerg remarked that all the reference circuits from u-blox and Atmel have a C-C-L circuit there, which strongly suggests that this is indeed all we need. - Rene noticed that the ATR0610 data sheet says that the input is prematched, meaning that it doesn't behave just like a 50 Ohm "standard" input, and that we're well advised to follow the reference designs. - Joerg suggested a value of 15 ... 22 pF for C7601. The values I found in the various reference designs range from 8.6 pF to 47 pF. Rene calculated the impedance for a few configurations, and they all ended up being very similar. - We have a 22 pF among the components removed. So I think 22 pF is a good start. In case we get horrible results, we can always swap it for different values. If nobody disagrees, then this should be the last change needed for ECN0008, and we can review and close that monster as well. - Werner _______________________________________________ gta02-core mailing list [email protected] https://lists.openmoko.org/mailman/listinfo/gta02-core
