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[ADRF6821_ Evalz] IF output frequency ?

Category: Software
Product Number: ADRF6821
Software Version: ADRF6821

Hi everyone,
I have one question. 
My application use RF/LO frequency: 400MHz-2.4Ghz and IF frequency: 100Khz-1MHz.
I have researched the ADRF6821, it is suitable my application. 
However, I really confused the minimum IF frequency when I use the ADRV6821 evaluation board.
Because the balun TC1-1-13MX+ wide band 4.5Mhz-3000Mhz.

Thank you so much.



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[edited by: KhaiPhan at 1:47 AM (GMT -4) on 2 Aug 2022]
  • Hi KhaiPhan,

    The balun mentioned in the user guide is used for single ended 50ohm measurement only to evaluate the part on the EVAL board. You may use the part at lower frequencies differentially without any balun, or single ended with a balun covering lower frequency.

    Thanks

  • Hi Salemdar, 

    Thanks for your quick response.
    I want to use the EVAL board but the EVAL board schematic uses balun TC1-1-13MX+.
    The datasheet: " The EVAL board is configured for single-ended outputs in default mode. For a single-ended I output, use the IF_I_OUT_POS connector with the on-board balun. For a single-ended Q output, use the IF_Q_OUT_NEG connector with the on-board balun."

    It means that
    - I can use single ended output I/Q with minimum IF frequency of 4.5MHz. If I use IF frequency lower 4.5Mhz, the performance is so bad. 
    - I can use differential signal I/Q with the IF frequency from DC to  500Mhz, right?


    Thank you so much.


  • Hi KhapPhan

    You may configure the resistors R31/R35 , R32/R36 to rout the RF signals directly to the SMA connectors and bypassing the balun. 

    There is also a DC block capacitor creating a low cut-off frequency. You may increase the value to go even lower frequencies when interfacing with a 50ohm instrumentation. If you match the output common mode voltage at the I/Q interface, you may also remove the DC-Block capacitor and go down to true DC. 

    Please take a look at the Fig56 of the datasheet as an example interface to an ADC

  • Hi Salemdar,

    Your answer is very clear. 


    Thank you so much.