UmTRXv2 samples expected shortage

Andrey Sviyazov andreysviyaz at gmail.com
Fri Nov 2 10:53:22 UTC 2012


Hi Alexander.

As I understand, you ask about output signal difference when TXVGA2=25,
isn't it?
Actually I missed it before.
I am sure that difference much less then 2-3dB as you mentioned, I think it
there was temperature effect.

Best regards,
Andrey Sviyazov.



2012/11/2 Alexander Chemeris <alexander.chemeris at gmail.com>

> Andrey,
>
> A stupid question. Why does "LDO" measurements have signal level 2-3dB
> higher then "FPGA" measurements? Is it due to measurement inaccuracy
> or it's an effect from the power supply change?
>
> On Fri, Nov 2, 2012 at 5:41 AM, Andrey Sviyazov <andreysviyaz at gmail.com>
> wrote:
> > Hi Jean-Samuel.
> >
> > I spent a lot of time yesterday and this morning because I trying to fix
> > DC-DC issue which I mentioned few days ago (see pics).
> > Unfortunatelly, result seems close to zero so far.
> > I never saw so strange problems with dc-dc converters before.
> > I am sure that there are no problems in v1 and also that this problems
> > because of syncro mode.
> > Now I am trying to describe this issue, may be anybody have experience
> with
> > this kind problem.
> > Let me know if you can help me here too.
> >
> > Regarding +3.3V LDO regulators for LMS.
> > Here attached pics of noise plots with LDO's and when supplied from
> > +3.3VFPGA through TI1608U601.
> > I can't find any significant difference there.
> > I think we can replace LDO's by RF chokes without derating performances.
> > In this case, power consumption decreased to 11..12W in dependance of
> values
> > TXVGA.
> >
> > Regarding GSM spectrum requirements you mentioned.
> > As you can see, yesterday I've measured it again when made experiments
> > around +3.3V.
> > I found that we didn't meet requirements only when deep saturation occur.
> > I mean when TXVGA2 higher then 23 (i.e. 24 and 25).
> >
> > Best regards,
> > Andrey Sviyazov.
> >
> >
> >
> > 2012/11/2 Jean-Samuel Najnudel - BJT PARTNERS SARL <jsn at bjtpartners.com>
> >>
> >> Hi Andrey,
> >>
> >>
> >> Thank you very muchf or your reply.
> >>
> >> Regarding the requirement at f +/- 400 KHz, the spec mentions our signal
> >> must be -60 dBc bellow the signal at f.
> >> You can get more details on the GSM 05.05 spec (part 4.2), from page 15.
> >> http://p3e.rats.fi/oh2mqk/GSM/GSM-05.05.pdf
> >>
> >> To pass this spec, we need to get our phase noise bellow -113 dBc/Hz at
> >> 400 KHz.
> >> On last measurements, we either fail or just pass this spec.
> >> If possible, this would be great to try to tune the charge pump and the
> >> loop filter passives to get our phase noise as low as possible.
> >> I know you already worked on this and already improved this but, if you
> >> have some ideas to decrease a bit more the phase noise, this would be
> very
> >> interesting.
> >>
> >> Best regards.
> >>
> >> Jean-Samuel.
> >> :-)
> >>
> >>
> >>
> >> On Wed, Oct 31, 2012 at 10:19 PM, Andrey Sviyazov <
> andreysviyaz at gmail.com>
> >> wrote:
> >>>
> >>> Hi Jean-Samuel.
> >>>
> >>> About power consumption and performancea I can say that spurs at 500
> kHz
> >>> offset around 6dB above TX LO noise plot.
> >>> It wad measured when 3.3V come from dogs through TI2012U601.
> >>> Tomorrow I'll measure all again and share pics in this topic.
> >>> As I mentioned, I'll try to find better filter to suppress 500kHz.
> >>> Please let me know any partnumbers or suppliers you known.
> >>> Also unoccupied place under 3.3V LDO's near LMS seems a good place for
> >>> thermal sensors.
> >>> About rf connectors, now I am sure that MCX much better then U_FL and
> we
> >>> should return them.
> >>> To connect UmSEL to UmTRX v2.1 required U_FL-MCX cable assemblies till
> >>> new UmSEL version.
> >>> Also possible to use direct cable soldering to UmSEL board.
> >>> Of course, last variant look not perfect.
> >>> About requirements at 400kHz we can't meet, I actually can't understand
> >>> what do you mean.
> >>>
> >>>
> >>>
> >>> Best regards,
> >>> Andrey Sviyazov.
> >>> (Sent from my mobile client)
> >>>
> >>> 31.10.2012 22:47 пользователь "Jean-Samuel Najnudel - BJT PARTNERS
> SARL"
> >>> <jsn at bjtpartners.com> написал:
> >>>
> >>>> Hi Andrey,
> >>>>
> >>>> Do you think it will be possible to decrease the power consumption and
> >>>> to keep the best possible performances for industrial applications ?
> >>>> I know you cannot be sure about this but I would like to know how
> >>>> confident you feel about this ?
> >>>>
> >>>> Best regards.
> >>>>
> >>>> Jean-Samuel.
> >>>> :-)
> >>>>
> >>>>
> >>>> On Wed, Oct 31, 2012 at 7:40 PM, Andrey Sviyazov
> >>>> <andreysviyaz at gmail.com> wrote:
> >>>>>
> >>>>> Hi Jean-Samuel, Alexander.
> >>>>>
> >>>>> Tomorrow I'll let you know what possible to make on time.
> >>>>> And we should set time limit for this.
> >>>>> For example, next morning.
> >>>>>
> >>>>> Best regards,
> >>>>> Andrey Sviyazov.
> >>>>> (Sent from my mobile client)
> >>>>>
> >>>>> 31.10.2012 22:24 пользователь "Jean-Samuel Najnudel - BJT PARTNERS
> >>>>> SARL" <jsn at bjtpartners.com> написал:
> >>>>>
> >>>>>> Hi Alexander,
> >>>>>>
> >>>>>> Thank you very much for your reply.
> >>>>>>
> >>>>>> Why skip/populate LMS power supply block ?
> >>>>>> As I understand we always need the LMS power supply block. I
> probably
> >>>>>> missed something. Could you explain this in more details to let me
> better
> >>>>>> understand ?
> >>>>>>
> >>>>>> Thanks a lot for your help.
> >>>>>>
> >>>>>> Best regards.
> >>>>>>
> >>>>>> Jean-Samuel.
> >>>>>> :-)
> >>>>>>
> >>>>>>
> >>>>>> On Wed, Oct 31, 2012 at 7:14 PM, Alexander Chemeris
> >>>>>> <alexander.chemeris at gmail.com> wrote:
> >>>>>>>
> >>>>>>> Yes, lesser input voltage range makes sense only if it saves >$10
> >>>>>>> and/or considerably increases power efficiency. I think this not
> the
> >>>>>>> case, and then only these changes will be needed:
> >>>>>>>
> >>>>>>> * traditional power connector
> >>>>>>> * MCX RF connector, because they sustain much more
> connect-disconnect
> >>>>>>> cycles
> >>>>>>> * lower power consumption mod
> >>>>>>>
> >>>>>>> I would appreciate if we could keep the same PCB for both versions
> >>>>>>> and
> >>>>>>> populate the proper version of power connector/RF connector and
> >>>>>>> skip/populate LMS power supply block.
> >>>>>>>
> >>>>>>> On Wed, Oct 31, 2012 at 9:56 PM, Jean-Samuel Najnudel - BJT
> PARTNERS
> >>>>>>> SARL <jsn at bjtpartners.com> wrote:
> >>>>>>> > Hi Alexander,
> >>>>>>> >
> >>>>>>> > This would be much easier to have the same board for both lab and
> >>>>>>> > deployment. Only the UmSEL would make the difference.
> >>>>>>> > For deployment, I really need wide input voltage range as I plan
> to
> >>>>>>> > power
> >>>>>>> > the whole system (UmTRX + PA) with a single 28V supply.
> >>>>>>> > Even if this can save a few euros, I would really prefer we do
> not
> >>>>>>> > make the
> >>>>>>> > input voltage range smaller.
> >>>>>>> > By the way, even for lab, it might be convenient and it can avoid
> >>>>>>> > damages in
> >>>>>>> > case of wrong voltage supply.
> >>>>>>> >
> >>>>>>> > Best regards.
> >>>>>>> >
> >>>>>>> > Jean-Samuel.
> >>>>>>> > :-)
> >>>>>>> >
> >>>>>>> >
> >>>>>>> >
> >>>>>>> > On Wed, Oct 31, 2012 at 6:50 PM, Alexander Chemeris
> >>>>>>> > <alexander.chemeris at gmail.com> wrote:
> >>>>>>> >>
> >>>>>>> >> Andrey, how much time do you need to create 2.1? If it's mire
> than
> >>>>>>> >> a day,
> >>>>>>> >> we should postpone this. I believe that enclosure is a much more
> >>>>>>> >> important
> >>>>>>> >> issue at this moment.
> >>>>>>> >>
> >>>>>>> >> I think we need following changes for the lab version:
> >>>>>>> >> * traditional power connector
> >>>>>>> >> * MCX RF connector, because they sustain much more
> >>>>>>> >> connect-disconnect
> >>>>>>> >> cycles
> >>>>>>> >> * lower power consumption mod
> >>>>>>> >> * smaller input voltage range (only if this makes things
> cheaper)
> >>>>>>> >>
> >>>>>>> >> Sent from my Android device.
> >>>>>>> >>
> >>>>>>> >> --
> >>>>>>> >> Regards,
> >>>>>>> >> Alexander Chemeris
> >>>>>>> >> CEO, Fairwaves LLC
> >>>>>>> >> http://fairwaves.ru
> >>>>>>> >>
> >>>>>>> >> 31.10.2012 14:05 пользователь "Andrey Sviyazov"
> >>>>>>> >> <andreysviyaz at gmail.com>
> >>>>>>> >> написал:
> >>>>>>> >>
> >>>>>>> >>> Hi Jean-Samuel.
> >>>>>>> >>>
> >>>>>>> >>> First of all, you didn't said about delay duration :)
> >>>>>>> >>> I can't delay this batch just due to my wishes that each next
> >>>>>>> >>> batch
> >>>>>>> >>> should work more and more ideally.
> >>>>>>> >>>
> >>>>>>> >>>> These modifications looks interesting. I think it is a good
> >>>>>>> >>>> idea.
> >>>>>>> >>>
> >>>>>>> >>> Hope so.
> >>>>>>> >>>
> >>>>>>> >>>>
> >>>>>>> >>>> I just have a few question.
> >>>>>>> >>>>
> >>>>>>> >>>> Why do you call this board revision 2.1 "a special batch for
> >>>>>>> >>>> labs" ?
> >>>>>>> >>>> Would these modifications make this revision 2.1 also more
> >>>>>>> >>>> suitable for
> >>>>>>> >>>> field deployment, at least as much as the revision 2.0 ?
> >>>>>>> >>>
> >>>>>>> >>> Because of I can fix only known issues.
> >>>>>>> >>> Also not all really required improvements are known yet.
> >>>>>>> >>>
> >>>>>>> >>>> Decreasing power consumption to 10..11 W would be great. Is
> >>>>>>> >>>> there any
> >>>>>>> >>>> drawbacks of this modification ? Would it decrease some
> >>>>>>> >>>> performances ? If
> >>>>>>> >>>> not, this modifiction to decrease power consumption is a
> >>>>>>> >>>> significant very
> >>>>>>> >>>> good modification.
> >>>>>>> >>>
> >>>>>>> >>> Decreasing of performances it is only spurs with DC/DC
> conversion
> >>>>>>> >>> freq
> >>>>>>> >>> ~500kHz.
> >>>>>>> >>> Now I searching more good LC filter to suppress it better than
> >>>>>>> >>> TI2012U601
> >>>>>>> >>> can.
> >>>>>>> >>>
> >>>>>>> >>>> Do you have enough space on the board to replace some U_FL
> >>>>>>> >>>> connectors
> >>>>>>> >>>> with MCX connectors as you suggest ?
> >>>>>>> >>>
> >>>>>>> >>> Yes, but may be not all should be MCX.
> >>>>>>> >>> Of course I did not insist, but just asking whether there is a
> >>>>>>> >>> reason to
> >>>>>>> >>> do it or not.
> >>>>>>> >>>
> >>>>>>> >>>> An external LNA would probably need around 5 Volts instead of
> >>>>>>> >>>> 6V. A
> >>>>>>> >>>> small PA would probably need a little bit higher voltage. Do
> you
> >>>>>>> >>>> think it
> >>>>>>> >>>> would be possible to have a variable voltage low power
> connector
> >>>>>>> >>>> ?
> >>>>>>> >>>
> >>>>>>> >>> On my opinion, variable voltage is not good idea.
> >>>>>>> >>> For example for LNA's better to place low noise LDO 6V to 5V
> near
> >>>>>>> >>> to IC's
> >>>>>>> >>> to get Vcc clean too.
> >>>>>>> >>>
> >>>>>>> >>>> By the way, could you pelase also add the 2 LMS output
> matching
> >>>>>>> >>>> capacitors we need to improve output power figures in the 1800
> >>>>>>> >>>> band ?
> >>>>>>> >>>
> >>>>>>> >>> Of course, because it is issue which should be fixed, but not
> >>>>>>> >>> improvement.
> >>>>>>> >>>
> >>>>>>> >>> Best regards,
> >>>>>>> >>> Andrey Sviyazov.
> >>>>>>> >
> >>>>>>> >
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>> --
> >>>>>>> Regards,
> >>>>>>> Alexander Chemeris.
> >>>>>>> CEO, Fairwaves LLC / ООО УмРадио
> >>>>>>> http://fairwaves.ru
> >>>>>>
> >>>>>>
> >>>>
> >>
> >
>
>
>
> --
> Regards,
> Alexander Chemeris.
> CEO, Fairwaves LLC / ООО УмРадио
> http://fairwaves.ru
>
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