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CCS/AWR1843BOOST: The meaning of rxGain in the profile configuration

Rata Zhang
Expert 2840 points
Part Number: AWR1843BOOST
Other Parts Discussed in Thread: IWR6843

Tool/software: Code Composer Studio

Hi,

  There is a parameter rxGain in the profile configuration.Its brief is shown as below:

 b5:0  Code for Rx VGA gain\n
                      1 LSB = 1 dB\n
                      Valid values: all even values from 24 to 52\n
 b7:6  Code for RF gain target (Not applicable for IWR6843 ES1.0, \n
                      RF gain is fixed to 34dB) \n
                      00 - 30 dB \n
                      01 - 34 dB \n
                      10 - RESERVED \n
                      11 - 26 dB \n
b15:8 RESERVED \n
                In IWR6843 ES1.0 device, Rx Gain is not accurate and not calibrated. \n
                The RF gain is 34dB and total Rx gain can be varied from 28dB to 56dB \n

In the above description,what is the meaning of the Rx VGA gain? And what is the RF gain target?What effect do they have for the radar receive signal?

Thanks,

Regards,

Rata

  • 0
    TI__Guru 58035 points

    Hello Rata,

    The  Rx chain consists of RF section (before the mixer) and IF section (after the mixer). In the complete Rx gain programming we provide flexibility to control the gains from both these sections. The RF gain target is the gain of the Rf section and complete Rx gain.

    The bits <5:0> actually set the complete Rx gain , not the VGA gain (you can refer to the Interface Control document) . We will correct this in the mmwave link documentation

    regards,
    Vivek

  • 0 in reply to Vivek Dham
    Expert 2840 points

    Hi Vivek，

        From your reply, I still have some doubts.Can I understand taht like this?The complete Rx gain consists of two parts,the RF section gain and IF section gain.And the RF gain target only refers to the RFsection gain.If I set the complete Rx gain as 52dB,the RF section gain as 30dB,then the IF section gain is 22dB，is that right? BTW.whether the gain value the higher ,the better.How should I choose the gain value?

    Thanks,

    Regards,

    Rata

  • 0 in reply to Rata Zhang
    TI__Guru 58035 points

    Hello Rata,

    Your understanding is correct regarding the RF and IF gain.

    Higher gain typically provides better noise figure but the P1dB compression will be poorer. So its a trade off based on your use case. Below is a plot that indicates this trade off across gain settings. Beyond 40db Rx gain the improvement in noise figure is very minimal.

    Regards,

    vivek

     

  • 0 in reply to Vivek Dham
    Expert 2840 points

    Hi vivek,

         Thanks for your reply,you said 'Below is a plot that indicates this trade off across gain settings.', but I can not see it, can you show it again?

    Thanks,

    Regards,

    Rata

  • 0 in reply to Rata Zhang
    TI__Guru 58035 points

    Hello Rata,

    Sorry, looks like image did not get attached. Trying it again.

    Regards,
    vivek

  • 0 in reply to Vivek Dham
    Expert 2840 points

    Hi vivek,

       Thanks for your reply, I got it.

    Regards,

    Rata