UmTRX preselector

Andrey Sviyazov andreysviyaz at gmail.com
Wed Aug 8 17:15:27 UTC 2012


2012/8/8 Jean-Samuel Najnudel - BJT PARTNERS SARL <jsn at bjtpartners.com>

> Hi Andrey,
>
> Thank you very much for your reply.
>
> I understand your point of view regarding the ADF4350. I agree with you,
> the ADF4350 still have quite good performances. I also agree that easier
> software support is also important. It would just be a great news if we
> could pass the GSM spec, at least as micro BTS.
>
> Regarding the GSM 1800 version of the selectivity board, it will not be a
> problem to change the mixer and the filters. However, are you sure we will
> be able to get the correct matching if we only change the passives ? Are
> you sure we would not need to modify the PCB traces to get a good matching
> for a 1800 MHz version of the board ? What do you think ?
>
Most of cooper would be 50 Ohm, so only FR-4 losses a bit higher.
Also RF cables losses and so on, therefore 1800 parameters will be a bit
worse, but it typical.
About components, I've checked again and found that RF SAW filter for 1800
UL require coil at input (added).

Best regards,
Andrey Sviyazov.



>
> Best regards.
>
> Jean-Samuel.
> :-)
>
>
>
> On Tue, Aug 7, 2012 at 7:27 PM, Andrey Sviyazov <andreysviyaz at gmail.com>wrote:
>
>> Hi Jean-Samuel.
>>
>> 1/ A few weeks ago, we discussed together about phase noise issues to be
>>> able to pass the GSM spec. You explained HMC830LP6GE has much better
>>> performances than the ADF4350. I know the HMC830LP6GE is a bit more
>>> expensive but, as discussed together before, I really believe this worth
>>> the extra cost. This would allow us to pass the macro or at least micro BTS
>>> specs without the need for designing another slectivity board. This would
>>> save a lot of work. Moreover, we espcially need this preselectivity board
>>> for a micro or even macro BTS. In this use case, I really believe price
>>> difference (like 40 or 50 USD) will be very low, especially compared to all
>>> other costs of a mid-long range micro/macro BTS installation. Unless you
>>> really disagree, I would really suggest to use the best performance
>>> components as we reasonably can.
>>>
>>
>> First of all, Robin said that ADF4350 already supported by UHD therefore
>> it could save time to implement it for UmTRX.
>> 2nd, I think that parameters differences isn't really as significant (few
>> dB) as price and soft changing time cost.
>> 3rd, it isn't last design and I am sure that we will change it for more
>> functions, performances and for housing adaptations.
>> Also I'm planing to buy HP4352 to design and measure PLL's, so of course
>> I'll test HMC830 too, but now we just have to be sure that it will work
>> properly and without risks.
>>
>>
>>> 2/ In my deployment in Mayotte, I will also deploy GSM 1800 band base
>>> stations because most of the spectrum I have is in this frequency band. To
>>> avoid making another PCB for GSM 1800, could you design the board to allow
>>> to populate either GSM 900 or GSM 1800 filters and matching passives with
>>> the same PCB copper ? A single PCB would be easier to test and to maintain.
>>> Moreover, this would save some costs as we will be able to order lager PCB
>>> volumes. This could make a quite significant saving. Please let me know
>>> what you think about this.
>>>
>> As I mentioned before, there are band specific components with same
>> footprint.
>> So, there are no changes required in PCB design for 1800 band, only BOM.
>> For example, HMC485 instead of HMC483 and FAR-F6KA-1G7475 instead of
>> FAR-F5KA-897.
>>
>> Best regards,
>> Andrey Sviyazov.
>>
>>
>>
>>>
>>> Anyway, thank you very much for this design. With UmTRX, this would
>>> really make a cost effective and great performances base station. Thanks a
>>> lot.
>>>
>>> By the way, as I am abroad, I may take a bit more time than usual to
>>> reply to your e-mails. I really appologize for this and I will do my best
>>> to reply as soon as I can.
>>>
>>> Best regards.
>>>
>>> Jean-Samuel.
>>> :-)
>>>
>>>
>>>
>>> On Mon, Aug 6, 2012 at 5:07 PM, Andrey Sviyazov <andreysviyaz at gmail.com>wrote:
>>>
>>>> I've found first error:
>>>> Missed AC block required for Vref pin of ADF4350.
>>>> Also translated some components descriptions to English to avoid
>>>> misunderstanding of Russian.
>>>> All newest files here in zip.
>>>>
>>>> Best regards,
>>>> Andrey Sviyazov.
>>>>
>>>>
>>>>
>>>> 2012/8/6 Andrey Sviyazov <andreysviyaz at gmail.com>
>>>>
>>>>> Sorry.
>>>>> Zip file here :)
>>>>>
>>>>> Best regards,
>>>>> Andrey Sviyazov.
>>>>>
>>>>>
>>>>>
>>>>> 2012/8/6 Andrey Sviyazov <andreysviyaz at gmail.com>
>>>>>
>>>>>> Hi all.
>>>>>>
>>>>>> Here first release of preselector project, schema and BOM.
>>>>>> Any questions and suggestions welcomed.
>>>>>>
>>>>>> Best regards,
>>>>>> Andrey Sviyazov.
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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