Topic: Noise figure  (Read 10185 times)

gavv_dms December 03, 2013, 04:19 AM

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Hi all, I'd like to calculate the noise figure of the board for the rx part and in particular the LNA that is at the beginning of the chain. In the datasheet there is a lna_out port, unfortunately I haven't been able to find a pin with such name. Any clue about this? Anyone knows where to find the datasheet for the LNA?
  • « Last Edit: December 03, 2013, 06:11 AM by gavv_dms »

arnaudNL December 03, 2013, 05:43 AM (#1)

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Dear Sir,


The LNA component is a SKY67101-396LF and the pin mapping is at the following:


1 N/C
2 RFIN
3 RFGND
4 VIN
5 FEEDBACK
6 N/C
7 RFOUT/VDD
8 N/C
9 Thermal Pad


There is a serie RC (R=51Ohm and C=3.3pF) between pin 7 and pin 5.


Best Regards,
Arnaud



gavv_dms December 03, 2013, 06:26 AM (#2)

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Dear Sir,


The LNA component is a SKY67101-396LF and the pin mapping is at the following:


1 N/C
2 RFIN
3 RFGND
4 VIN
5 FEEDBACK
6 N/C
7 RFOUT/VDD
8 N/C
9 Thermal Pad


There is a serie RC (R=51Ohm and C=3.3pF) between pin 7 and pin 5.


Best Regards,
Arnaud


Thanks a lot for your answer, my doubt is that we are using a FMC30RF board with rf coverage between 1200 MHz -3000 MHz, so I'd like to know if my board use the SKY67101-396LF or another LNA due to differnent RF.
In the FMC30RF  datasheet ther is a LNA_OUT pin (it's written that it's not avaiable from the front panel) but, if possible, I'd like to measure it's output, how can I measure it?
Best regards,
Giovanni

arnaudNL December 03, 2013, 08:14 AM (#3)

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Dear Giovanni,


You have a FMC30RF with high range option. I checked the BOM and the exact LNA part number is SKY6710-396LF. The low range option has a SKY67101-396LF instead. I don't have direct link to the datasheet unfortunately; The FMC30RF was driven by Texas Instruments, they had a RF development board and we have been asked to redesign this board as an FMC board keeping the same components on the board.


The lna_out signal goes on some resistors but they are all caged by the Faraday cage and removing the metal casing is not an option.


Best Regards,
Arnaud

jmpg December 10, 2014, 12:26 PM (#4)

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You have a FMC30RF with high range option. I checked the BOM and the exact LNA part number is SKY6710-396LF. The low range option has a SKY67101-396LF instead.


Dear Arnaud,


I think there is missing a number in the LNA reference: SKY6710X-396LF


See the next pdf with the LNA family. Depending on that last number the target frequency is very different:
http://www.skyworksinc.com/uploads/documents/bro394_12.pdf


Can you tell me the exact part number?


Best regards,
Jose
  • « Last Edit: December 10, 2014, 12:29 PM by jmpg »

arnaudNL December 11, 2014, 07:20 AM (#5)

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Jose,


Sorry for that, the complete part number is SKY67100-396LF


Best Regards,
Arnaud

jmpg December 11, 2014, 07:25 AM (#6)

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Thanks Arnaud,


But that LNA operating frequency range is only 1.7-2.0 GHz.


Best regards,

arnaudNL December 11, 2014, 08:09 AM (#7)

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Dear Jose,


Well, depends if you look at the preliminary datasheet (http://www.cdiweb.com/datasheets/skyworks/201265C.pdf) or the actual current datasheet (http://www.skyworksinc.com/uploads/documents/SKY67100_396LF_201265I.pdf) from Skyworks directly.


I do feel that a bit odd but I cannot imagine the designer to be so light. Also you should know Texas Instruments driven this design. They have asked us to port a huge RF board (or two) they had into FMC form factor, schematics were reviewed by TI and the board was characterized by TI so I would not expect such a design flaw.


Best Regards,
Arnaud

jmpg December 11, 2014, 08:41 AM (#8)

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Ok, thanks for references Arnaud

arnaudNL December 11, 2014, 09:26 AM (#9)

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This topic is being closed because the issue is considered as resolved by 4DSP. Feel free to create a new topic for any further inquiries.