LNA and Noise Figure improvement

Andrey Sviyazov andreysviyaz at gmail.com
Tue Oct 30 16:02:06 UTC 2012

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
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