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Jean-Samuel Najnudel - BJT PARTNERS SARL jsn at bjtpartners.comHi Andrey, Would you have some updates about your NF calculations in both 900 (MGA-13116) and 1800 (MGA-13216) bands ? This information would be very interesting to figure out if we need an external 1st stage LNA in front of the UmSEL Rx path. Thanks a lot for your kind help regarding this front-end related question. Best regards. Jean-Samuel. :-) On Tue, Oct 30, 2012 at 5:02 PM, Andrey Sviyazov <andreysviyaz at gmail.com>wrote: > HI 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/20121102/b1ff2b75/attachment.htm>