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Is LMX2541 the best solution?

Syed Raza
Prodigy 40 points
Other Parts Discussed in Thread: LMX2541, LMX2531

I want to create a 2.8GHz Ultra Low Noise LO, using a 87.5MHz TCXO reference and an external 2.8GHz CRO.  Is LMX2541 my best choice for phase noise, rms jitter and cost?

Thanks

  • 0
    TI__Mastermind 27581 points

    Syed,

     

    The LMX2541 is an excellent choice and has both a low PLL 1/f noise and excellent figure of merit.    This is likely to be your lowest jitter solution.

    If you want lower cost or current, there are probably other solutions that sarifice jitter.  The LMX2531 would normally do this, but the input only goes up to 80 MHz, not 87.5 MHz, so you might need to divide this down for this part.   But aside from this, unless you want a lot of outputs, like something from the LMK04800 family, I think that the LMX2541 is the best choice.

     

    Regards,
    Dean

  • 0 in reply to Dean Banerjee
    Prodigy 40 points

    Dean:  Thank you so much.

    When you have some time, can you give me a call please; I have some additional questions on the loop filter in this scheme & on the Evaluation Board for LMX2541.

    Regards,

    Syed

  • 0 in reply to Syed Raza
    Prodigy 40 points

    Also, I would like to procure an Evaluation Board to start working with the LMX2541 with an external VCO.  There are (6) variations in stock at Digikey.  Which one is the correct one to procure?

    Thanks,

    Syed

  • 0 in reply to Syed Raza
    TI__Mastermind 27581 points

    Syed,

    The difference between these options is the VCO frequency;  the PLL  is exactly the same. 

    Because you are bypassing the internal VCO, it makes no difference what version you choose.

    Regards,

    Dean

  • 0 in reply to Dean Banerjee
    Prodigy 40 points

    Dean:  Thank you for the explanation.

    I will procure one from Digikey then.

    I do have additional questions regarding the loop BW limitations.  Would it be possible to communicate via email? My address is sraza@abracon.com

    Thanks

    Syed