UmTRXv2 samples expected shortage

Jean-Samuel Najnudel - BJT PARTNERS SARL jsn at bjtpartners.com
Fri Nov 2 10:10:49 UTC 2012


Hi Andrey,

Thank you very much for your reply.

This is a good news we can decrease the power consumption without derating
performances.
This power decrease is really great both for lab and industrial use.

Regarding the GSM spectrum requirements, I seems we pass the spec. This is
a very good news.
This is not a problem to fail on highest TVGA2 gain. Anyway, at saturation,
LMS6002D power dissipation becomes really high and can be a problem. I
actually do not intend to push the TVGA2 gain as high as 25.

However, I still have a few questions about this.
I agree it passes the spec but it just pass, for this board. I am a still
bit afraid some boards among the production might fail this spec. Do you
think we could find a way to decrease a bit more this phase noise ?
By the way, did you measured this spectrum for the GSM 1800 band ? Do we
still pass the spec ? Did you tried when you increase a bit the temperature
and check how it behaves ?

Anyway, thanks a lot for these measurements you did.

Best regards.

Jean-Samuel.
:-)


On Fri, Nov 2, 2012 at 10:41 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
>>>>>>>
>>>>>>
>>>>>>
>>>>
>>
>
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