Using HMC698 PLL with 10 MHz reference

I'm building a PLL using HMC698, and I have to work with a 10 MHz sine wave as reference. The phase noise of the 10 MHz is -135 at 10 Hz and -155 at 100 Hz. The HMC698 datasheet doesn't have phase noise data at 10 MHz, does anyone has data on that. Also, what is the recommended way to convert a sine to square wave while preserving the low phase noise of the input signal?

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    •  Analog Employees 
    on May 18, 2017 5:10 PM

    Hi there,

    The residual phase noise performance of the phase detector used in the HMC698 is similar to the HMC3716. There's a plot at 10MHz using a square wave which as you know is what's required at this very low frequency.

    As far as "converting" your 10MHz sine wave to a square wave, I recommend using a comparator circuit (use one of Analogs high speed comparators) alternatively diodes (to rectify) or an RLC circuit can be used to clip the signal also. Depending on your approach you may need to amplify the signal to meet the minimum input sensitivity level for the HMC698. Of course nothing is free, all of these methods add their own noise contribution.

    Best Regards,

    Marty

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  • 0
    •  Analog Employees 
    on May 18, 2017 5:10 PM

    Hi there,

    The residual phase noise performance of the phase detector used in the HMC698 is similar to the HMC3716. There's a plot at 10MHz using a square wave which as you know is what's required at this very low frequency.

    As far as "converting" your 10MHz sine wave to a square wave, I recommend using a comparator circuit (use one of Analogs high speed comparators) alternatively diodes (to rectify) or an RLC circuit can be used to clip the signal also. Depending on your approach you may need to amplify the signal to meet the minimum input sensitivity level for the HMC698. Of course nothing is free, all of these methods add their own noise contribution.

    Best Regards,

    Marty

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