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IWR6843AOP: Input Clock

Ohad Bonneh
Intellectual 1960 points
Part Number: IWR6843AOP
Other Parts Discussed in Thread: IWR2944

Tool/software:

Hi Team, 

what would be the performance differences of the device is I'm using external VCO vs Oscillator?  

How would this affect the mmWave? can you explain what might be the tradeoffs of each? 

Thanks! 

  • 0
    TI__Genius 11750 points

    Hi

    Thanks for your query. Please allow us a couple of days to respond

    Regards

  • 0
    TI__Expert 3720 points

    Hi There,

    External oscillator can be used to source the 40MHz clock in IWR6843AOP.

    Please do follow the data sheet spec for the external oscillator:

    In the case where an external clock is used as the clock resource, the signal is fed to the CLKP pin only; CLKM is grounded. The phase noise requirement is very important when a 40-MHz clock is fed externally. Table above lists the electrical characteristics of the external clock signal.

    There would not be trade of as such if the data sheet spec is followed for the external clock source.

    Thanks,

    Swarnendu

  • 0 in reply to Swarnendu Chattopadhyay
    TI__Intellectual 1960 points

    Hi Swarnendu, 

    Thanks for your reply!

    I'm having 2 concerns, 

    1) these values looks a bit relaxed, in other radar systems i see much strict requirements regarding the phase noise of the reference clock can you elaborate more on that subject and how we can "get away" with such relaxed reference?   

    2) Have we tested the performance of the system with temperature cycles / vibrations and ect? isnt crystal is more prone to deviation resulting bad performances?     

  • 0 in reply to Ohad Bonneh
    TI__Expert 3720 points

    Hi Ohad,

    1) When you say, "other radar systems" do you refer to any specific radar system? Could you specify?

    These specs referred in the IWR6843AOP data sheet works well for the low power radar (IWRLx432) as well as IWR2944 kind of radar devices.

    2) Yes, these values given in the data sheet are tested.

    The XTAL tolerance specified in the data sheet includes initial tolerance of the crystal, drift over temperature, aging and frequency pulling due to incorrect load capacitance. Therefore, the XTAL could be selected that has the required tolerance to ensure avoiding XTAL related performance degradation.

    The specs in the data sheet are considering in general use cases. If any particular application demands tighter XTAL/CLK specifications, it could be selected accordingly.

    Thanks,

    Swarnendu