AD9361 pico BTS design

I have a customer designing a pico cell GSM BTS for both 900MHz and 1800MHz. They are using an ADF4350 PLL as the LO source. So far, all testing indicates that the blocking and sensitivity requirements are not limited by the phase noise of the ADF4350.

We've loaded up the GSM.ini file that comes with the AD9361 software package, have a few questions;

1. Is the gain table in this GSM.ini file optimized for GSM pico BTS or was it done for macro cell, or something else?

2. Same question for analog and digital filter settings. If not, do you have recommendations for filter settings for GSM pico cell?

3. Is there a noise figure vs. LNA gain curve for the AD9361? The Simulink model indicates that noise figure is nearly constant with gain. but I would like confirmation that this is true.

thanks,

Steve

  • 0
    •  Analog Employees 
    on Jul 17, 2019 10:04 PM

    One more question. I think the analog filter is integrated with the sigma delta ADC on the AD9361, is that correct? If so, what does the analog filter response curve look like when the ADC is sampling at 0.541MSPS? 

  • 0
    •  Analog Employees 
    on Jul 18, 2019 10:01 AM in reply to stevereine
    1. Is the gain table in this GSM.ini file optimized for GSM pico BTS or was it done for macro cell, or something else?

    GSM.ini file is not loading any gain table. It is configuring the required filter configuration. You can open and read GSM.ini file in notepad++ tool.

    The software package of AD9361 has Full gain table and Split gain table. Which customer has to evaluate against their system requirement to confirm. We don't have any measured results against GSM standard from our reference design.

    2. Same question for analog and digital filter settings. If not, do you have recommendations for filter settings for GSM pico cell?

    GSM.ftr filter is available as part IIOScope GUI. Which customer has to evaluate against their system requirement to confirm. We don't have any measured results against GSM standard from our reference design.

    3. Is there a noise figure vs. LNA gain curve for the AD9361? The Simulink model indicates that noise figure is nearly constant with gain. but I would like confirmation that this is true.

    Please refer to the below link,

    https://ez.analog.com/wide-band-rf-transceivers/design-support/w/documents/10073/noise-figure-vs-gain-index-plots

    One more question. I think the analog filter is integrated with the sigma delta ADC on the AD9361, is that correct? If so, what does the analog filter response curve look like when the ADC is sampling at 0.541MSPS? 

    Analog filter is not part of sigma-delta ADC. Please refer to the below block diagram.

    Please refer to the below graph for analog filter response curve look like when the ADC is sampling at 0.541MSPS.

    Below is the excel file for the Frequency response.

    XLSX