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Phase-Lock-Loop vs Injection Locking

  1. Apr 24, 2014 #1
    Sorry it's been a while since I posed here. I'm working on a project for school that will involve sending a synchronizing signal to an oscillator on a reciever, which I know often uses a phase-lock-loop. However, I was doing some reading on injection-locking, and it seems that it would be easier to utilize than a circuit involving several mixers, filters, and variable reactance components. But dispite this I can't find any instances where it's used in a practical circuit, so it somehow seems to be less preferable than PLLs. I'm wondering if anyone knows why this is the case (why PLL are prefered over injection-locking).

  2. jcsd
  3. Apr 25, 2014 #2


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    Injection locking will lock the p'th harmonic of an oscillator to the q'th harmonic of a reference signal. Just which integer p/q ratio of harmonics can be hard to control or predict, and sometimes does not matter if drift is the only concern.

    A PLL synthesiser has well defined integer ratio p/q, (a swallow counter), that locks a local VCO to a predictable frequency.
  4. Apr 25, 2014 #3
    Okay, thanks! It makes more sense now.
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