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Charge pump vs. phase detector gain for a PLL

Discussion in 'Electronic Design' started by [email protected], Aug 17, 2006.

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  1. Guest

    When calculating PLL loop filter values, one need to know the phase
    detector gain in mA/Hz for a "charge pump phase detector". Very often
    the charge pump current is defined if you are using a synthesiser chip.
    My question is therefore: What is the relationship between phase
    detector gain in mA/Hz and charge pump current in mA?
    I often see in literature that they define the ratio between phase
    detector gain and charge pump current as a 1:1 ratio. But is this
    really correct?
     
  2. Jim Thompson

    Jim Thompson Guest

    That is not correct... it is mA/radian
    Nope. Read the data sheet more carefully.

    ...Jim Thompson
     
  3. Mark

    Mark Guest

    Yes. the gain is current / phase delta

    very often the data sheet will give you the full scale current output
    where full scale is +2pi radians (+360 degrees) and -2pi radians (-360
    degrees).

    Mark
     
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