Custom calypso board

Mathias K. kesmtp at freenet.de
Thu Jul 12 21:08:56 UTC 2012


On 12.07.2012 03:29, Sébastien Lorquet wrote:
> Le 12/07/2012 01:06, Joachim Steiger a écrit :
>> Harald Welte wrote:
>> [...]
>>> However, now that I think of it, PCIe requires PCB thickness to be
>>> different (1.5mm) from what we are hading for (more like .8 or 1mm).
>>>
>>> So I guess I'll scrap that idea.
>> what about making it 2 pcb?
>>
>> one 'gsm module' with 'plated half holes'* and or board to board conn.
>> one 'carrier board' which then has the right thickness for the pcie-con.
>>
>> that way the sandwhich is mechanical stable and the rf performance
>> shouldnt be tampered with and can even serve as additional shielding if
>> needed (e.g. make side opposite to the modem gnd flat).
>>
>> this makes the modules as small as possible for integration into
>> different kinds of carriers or even a full phone.
>>
>> what do you think?
>
> I was about to suggest the same thing.
> A very small 6-layer board with minimal/critical functionnality (not even the sim) and then let
> people integrate that into simpler PCBs.
> The RF can get out of the "critical" board via an UFL socket.
>
> In the past, wavecom (now sierra wireless) had this idea. They developed a modem core on a small
> PCB, using bga on the backside instead of plated half holes. The packaging was made with a metallic
> shielding box.

There are more other companies that go this way (look at bt or zigbee) and you can use this tiny 
boards with every cpu of your choice because the simple interface. I don't think this happens with 
this kind of special hardware. I really don't know if it make sense to use a separate rf-board and a 
main-board. Is there any chance to use this rf-board with another platform (fpga,dsp ...) then this 
would make sense and also decrease the price of this platform.



Regards,

Mathias





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