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IWR6843AOPEVM: IWR6843AOPEVM

Rakefet Weidenfeld
Prodigy 90 points
Part Number: IWR6843AOPEVM
Other Parts Discussed in Thread: IWR6843AOP, IWR6843

Hello

I'm using IWR6843AOP evaluation board  in FMCW mode for raw data capture.

Configuration is: 

When looking into range-Doppler map I see 2 strong spurs at constant range bins, with varying Doppler frequencies.

from previous Questions I understand this spurs are present when crossing 59.4 GHz and 62.1 GHz, as a result of VCO nonlinearity and leakage.

and are of constant frequency (which translates to range bin, depending on slope) and non-stable Doppler. Is that correct?

Also, is it's amplitude independent of received signal amplitude?

https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/880983/iwr6843-the-spur-of-the-tx-output-of-iwr6843

My questions are:

1. Does using frequency band  of 62.15 - 64 GHz suppose to eliminate the problem?

2. What do you mean by 59.4 GHz? Doesn't  IWR6843 start at 60 GHz?

3. Why do we see it also for relatively wide bandwidth (1.7GHz)?

4. Why is it so high on AOP version? when using 'simple' IWR6843 the problem was negligible.

5. Do you plan to correct that in future versions? If so, when is that suppose to happen?

Thanks in advance,

Rakefet

  • 0
    TI__Mastermind 30545 points

    Hello Rakefet,

    One of our hardware experts is looking into this ticket for you. They should get back to you this week.

    Regards,

    adrian 

  • 0
    TI__Genius 9695 points

    Hi Rakefet,

    I am following up on this. What revision of the AOP EVM do you have?

    Thanks,

    Eben.

  • 0
    Prodigy 90 points

    Hi Eben,

    we're using rev. F

    thanks

  • 0 in reply to Rakefet Weidenfeld
    TI__Mastermind 31680 points

    Hello Rakefet, 

    Sorry for the delay on this. Please find our response below : 

    1. The below linked highlights the updated Errata on this issue. As you can see, there is a non-linearity of the synthesizer when crossing all the below highlighted frequencies. 

    https://www.ti.com/lit/er/swrz092a/swrz092a.pdf 

    I believe this answers your first question. 

    2. The supported RF frequency band for 60GHz mmWave devices from the DFP support point of view is 57GHz to 64GHz. You can refer to the mmWave ICD for this purpose. 

    3. You would see the Spur effect more prominently if the RF bandwidth is smaller (say <500MHz). But for larger RF bandwidth, for eg. your case, this effect should be minimal. 

    4. That might depend a little on device on device due to process variation. 

    5. Currently, we do not have a timeline for this. Avoiding narrow bandwidth ramps is the only solution/suggestion we have to offer. 

    Hope this clarifies your concerns and gets you started. Please let us know if you have any other questions.

    Regards,

    Ishita