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AWR1642: Issue of fixed range with ghost point.

Jesse Wang
Intellectual 2285 points
Part Number: AWR1642

Hi,

 We designed an AWR1642 PCB for BSD application and found the test result always having a ghost point at fix range ~20m with a positive small doppler velocity.

 We tried to cut out the antenna traces, but the fix point is still at ~20m with a negative small velocity.

 We tried to remove DCDC for reducing the switching freq, and found the fix point is still at ~20m, but the doppler velocity becomes very large.

 What can be the reason to cause this symptom?

  • 0
    TI__Mastermind 25835 points

    Hello,

        Could you please share the differences between TI EVM (AWR1642BOOST). If there are differences (Schematic/Layout) in power supply design, Clocking design that must be examined carefully. 

    Have you followed schematic & Layout checklist for your PCB design?

    http://www.ti.com/lit/zip/swrr154

    Thanks and regards,

    CHETHAN KUMAR Y.B.

  • 0 in reply to CHETHAN KUMAR Y.B.
    TI__Intellectual 2285 points

    Hi Chethan,

     Thanks for advice. We are working on next version schematic / layout design. I will check again on the power / clock design and get back to you by email thread.

     A quick question: Is it possible the IF being interfered by power / clock, so it appears a fix range FFT point, with a fix Doppler FFT velocity?

  • 0 in reply to Jesse Wang
    TI__Mastermind 25835 points

    Hello Jesse,

       Yes,  IF signals could be interfered by power or clock system (leading to Local oscillator used for RF up-conversion and down-conversion), leading to corruption of IF signal could lead to fixed range FFT points or fixed Doppler FFT points. Hence these circuits need to be examined carefully. Power supply needs low noise/low ripple power delivery network, please review the supply requirements in the datasheet. 

    Thanks and regards,

    CHETHAN KUMAR Y.B.