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Split clock signal (provided by oscillator)

  1. Nov 5, 2016 #1

    i was wondering how its possible to split a clock signal provided by an oscillator in order to use it to drive multiple devices with this one split clock signal.
    Let's assume we have a kind of USB device (like an USB stick), that gets its clock signal from an oscillator.
    Let's say i would like to provide the same clock signal to multiple USB devices of the same kind (to synchronize them). Would it be possible to take the already build in oscillator out, split the clock signal of this oscillator, amplify it and then provide this clock signal to all devices so they all have the same clock signal?
    How would i amplify the clock signal? Could i just use an operational amplifier with no feedback to amplify the clock signal?

    At the moment i have no certain device, im just curious how this could be done?

    Thanks a lot!
  2. jcsd
  3. Nov 5, 2016 #2


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    If the digital clock source (Fosc) is external on the master clocked device then a simple clock buffer chip using that signal will work. Some devices have a internal oscillator with an output pin to drive external devices with a programmed configuration option for a external clock that may not be accessible on a production USB stick.
    3.3v device: http://www.ti.com/product/CDCLVC1112
  4. Nov 5, 2016 #3
    thanks for your reply!
    Im indeed talking about devices that all have internal oscillators only.
    So i had to remove the internal oscillator from the device first.
    After i would clock multiple devices of the same kind with one shared oscillator.
    But i guess i first had to amplify the given clock signal somehow in order to clock mutiple devices with it. (because its gonna be to weak after the signal split)
    Could i just amplify this signal using an omp amp (open loop gain configuration)?

  5. Nov 5, 2016 #4


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    Assuming the clock is a digital signal.
    Because of transmission line effects/fanout (current drive capability) and the need for clean,fast rise/fall times on the clock a proper digital driver would be better for any signals greater than maybe 1 MHz.
  6. Nov 7, 2016 #5


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    That depends. Measurements instruments usually use a 10 MHz sine as a external reference signal and will have a "ref in" and "ref out" connector at the back. In precision instruments (which I presume is what we are talking about here, not much point locking several instruments to the same oscillator otherwise) the oscillator is a loop and they can lock to an external reference as long as it is reasonably close to the internal reference.

    I don't think I've ever come across a digital clock being used as an external reference (not even in say backplanes of rackmounted equipment); it just seems like an unnecessary complication when you can so easily do clock recovery (and generate a digital clock) from a sinewave
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