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Andrey Sviyazov andreysviyaz at gmail.comHI Jean-Samuel. Not really sure to do UmTRXv3 right now. On my opinion now we should found as much issues as possible with v2. For example, now I am working with power consumptions. I have to think a bit about NF improvement you suggest. I'll let you know my calculations by tommorow. Best regards, Andrey Sviyazov. 2012/10/30 Alexander Chemeris <alexander.chemeris at gmail.com> > Forwarding to the mailing list. > > > ---------- Forwarded message ---------- > From: Jean-Samuel Najnudel - BJT PARTNERS SARL <jsn at bjtpartners.com> > Date: Tue, Oct 30, 2012 at 6:25 PM > Subject: LNA and Noise Figure improvement > > > Hi Andrey, > > I understand you plan to prepare the UmTRXv3. > > I would need to discuss about the Rx Noise Figure improvement. > With UmSEL, according to your calculations, NF would be around 0.7 dB > (excluding duplexer IL) with the MGA-13116. > It would be interesting to try to improve this figure with a very > first stage LNA based on the MGA-633P8. This would let us reach a NF > as low as about 0.4 dB. > > Adding this very first stage LNA in the Rx path brings a few questions. > > 1/ To improve isolation with the other RF parts, would we need to have > this LNA in a separate shielded enclosure ? > If yes, we would need a 5V power supply for this LNA. To have a better > shielding between the voltage regulator circuitery and the LNA, it > should be nice to have the 5V voltage regulator outside of the LNA > enclosure. To make this possible, it would be very useful to add a 5V > voltage regulator and connector on the UmTRXv3. > If not, we do not need specific modifications on the UmTRXv3 but we > would need to add an MGA-633P8/634P8 as a very first stage in the > UmSEL. > > 2/ Whatever external or on the UmSEL, this extra LNA will increase the > total gain. Considering your calculation, the UmSEL IIP3 is already as > low as around 1 dBm. If we add a very first stage LNA, this IIP3 will > go down to about -15 dBm. This could be a problem for inband blockers. > Even if, in real life situation in the field, I am not sure it will be > a very big problem, it will be a problem to pass the spec. > Would you have another idea to improve the NF ? > If not, could you please let me know what NF we could expect with the > current design (UmSEL with MGA-13116/13216) in both 900 and 1800 bands > ? > > Best regards. > > Jean-Samuel. > :-) > > > > > -- > Regards, > Alexander Chemeris. > CEO, Fairwaves LLC / ООО УмРадио > http://fairwaves.ru > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/umtrx/attachments/20121030/3d433c0b/attachment.htm>