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  1. #1
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    lock range

    Hi

    For a pll, why the lock range is more than the capture range??
    can any body expalin more clearly??

    thanks.

    •   Alt27th February 2007, 10:48

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  2. #2
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    capture range lock range

    Hope this will clear your doubt

    •Capture range
    frequency range over which PLL can lock on signal

    •Lock range
    frequency range over which PLL can track input variation

    Capture
    To be in the capture state their must be an external signal and the feedback loop must be closed.
    In the capture state the PLL is in the process of acquiring a lock.

    Lock
    In the lock state, the VCO output frequency is lock onto the (equal to) the frequency of the external input signal.
    In the lock state, the VCO output frequency tracks (follows) changes in the frequency of the external input in the external signal.



    •   Alt27th February 2007, 15:01

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  3. #3
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    lock range and capture range

    so, as i lock range , vco output frequency tracks the input frequency that means there is some change in input frequency which is getting tracked. The frequency up to which this tracking is possible is lock range. But , notice, there is tracking going on , i.e something is changing which is getting tracked. So this change in something should not be too large for the PLL to track the change. i.e. the change should be limited and this limit in the value of change (which can be tracked) is called capture range.

    Clearly , the change will be incremental and can't be larger than the range of frequency of your designed PLL.

    hope this makes more sense.

    thanks



    •   Alt13th July 2009, 06:11

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  4. #4
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    lock range capture range

    Quote Originally Posted by dkumar
    ... So this change in something should not be too large for the PLL to track the change. i.e. the change should be limited and this limit in the value of change (which can be tracked) is called capture range.
    ...
    hope this makes more sense.
    No, it doesn't, sorry. It's called lock range, s. kumards posting above!



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