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improving phase noise

Discussion in 'Electronic Design' started by Rene Tschaggelar, Oct 24, 2003.

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  1. Ian Buckner

    Ian Buckner Guest

    Sorry, I was unclear. I meant to suggest building a VCO using the SAW
    as the
    primary frequency defining element, with a varactor/phase shifter to
    get fine
    frequency control. Note that 70kHz/280MHz corresponds to a _very_ high
    Q.

    Do a google search on "SAW based VCO". The first hit at:
    www.icst.com/products/pdf/M630%2010GHZ.pdf
    gives a block diagram (more complex than you need).

    Regards
    Ian
     
  2. Guest

    well made SAW resonators have a Q that is limited by the acoustic loss
    of the quartz which reduces from a Q equivalent of 10million at 2MHz to
    1000 approaching 1GHz.
    The attractive thing about SAW resonators when compared to high
    frequency fundamental shear mode "crystals" is that the drive level can
    be quite high this makes >-174dbc noise floor possible.
    Close in noise is a function of the Q and will be better than LC or
    small DROs , magnetically tuned YAG oscillators are better but more
    expensive /clunky. VCO pulling in an oscillator will also be an inverse
    function of Q. Maximum pulling will be of the order of f/Q
     
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