ADF5902: How is the TX chirp range ?

Hi Teams

  We plan to use ADF5902+ADF5904 to develop 24G FMCW, There are two question need to confirm. thanks 

  1) Would you pls. check the chirp range of ADF5902 ?  Can it support TX slope above 4 mHz/uS ? 

2) Can support 2pcs ADF5902 and 4 pcs ADF5904 in parallel to realize 4TX 16RX ? 

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  • +1
    •  Analog Employees 
    on Sep 28, 2021 1:29 PM

    Hello,

    1) Fastest chirp speed will depend on things like the number of steps, PFD frequency, how linear the chirp needs to be and phase noise requirements/how wide you can make the loop filter BW. I would recommend downloading ADIsimPLL (free software) and simulating this yourself. Here is a short video which describes how to simulate chirps with ADisimPLL. There is no dedicated ADF5902 ADIsimPLL model but you can use ADF4159 as the PLL and ADF5901 as the VCO and it will be very close to ADF5902.

    2) Multiple Rx stages is generally not a problem. You just need to make sure the LO line is designed correctly with appropriate splitting such as a Wilkinson divider. We have done this with two ADF5904 chips and one ADF5901, but depending on your PCB losses splitting the LO into 4 may require additional circuitry such as an LNA, to ensure each ADF5604 gets enough signal power at the LO pin.

    Using multiple Tx chips is much more difficult and generally not something we recommend. See here

    Regards,

    Alex

Reply
  • +1
    •  Analog Employees 
    on Sep 28, 2021 1:29 PM

    Hello,

    1) Fastest chirp speed will depend on things like the number of steps, PFD frequency, how linear the chirp needs to be and phase noise requirements/how wide you can make the loop filter BW. I would recommend downloading ADIsimPLL (free software) and simulating this yourself. Here is a short video which describes how to simulate chirps with ADisimPLL. There is no dedicated ADF5902 ADIsimPLL model but you can use ADF4159 as the PLL and ADF5901 as the VCO and it will be very close to ADF5902.

    2) Multiple Rx stages is generally not a problem. You just need to make sure the LO line is designed correctly with appropriate splitting such as a Wilkinson divider. We have done this with two ADF5904 chips and one ADF5901, but depending on your PCB losses splitting the LO into 4 may require additional circuitry such as an LNA, to ensure each ADF5604 gets enough signal power at the LO pin.

    Using multiple Tx chips is much more difficult and generally not something we recommend. See here

    Regards,

    Alex

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