Electronics notes/Phase Locked Loop notes: Difference between revisions
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{{Electronics notes}} | {{Electronics notes}} | ||
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From a functional, 'why would you do this' level, a phase locked loop means making one | From a functional, 'why would you do this' level, a phase locked loop means making one oscillating thing follow another. | ||
For a (bad) analogy, take two oldschool car blinkers. | |||
These drift quickly {{comment|(While bimetal blinkers are roughly the clunkiest way to do this, even if you manufacture them extremely well they would still drift - the only question is how fast)}} | |||
Say you have two imprecise bimetal blinkers, and you could forcibly make one start ''when'' the other one triggers, then they would keep the same speed. | |||
Say you have two imprecise bimetal blinkers, and you could forcibly make one | |||
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PLL is a little more than that. | PLL is a little more than that. | ||
There are a few variant implementations, | |||
but they are generally described as | |||
"we have an oscillator, and you're feeding us a reference signal you want to synchronize to. | |||
we'll build a feedback system that will tune our own oscillator to match the reference, in phase and frequency" | |||
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: which is not very hard when it is a VCO -- because that means 'voltage controlled' | : which is not very hard when it is a VCO -- because that means 'voltage controlled' | ||
The phase difference detector only really gives sensible "slight corrections to keep it in phase" output when the VCO is already at more or less the right frequency. | |||
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* frequency synthesizers, which govern communication between chips {{verify}} | * frequency synthesizers, which govern communication between chips {{verify}} | ||
* creating copies of clocks, | |||
:: and having that be cleaner than the original | |||
* creating multiples a clock signal. | |||
* altered version to becomes a frequency multiplier | |||
* if you feed it audio, you will get some fuzz-like imitation | |||
The first few meaning they are common in communication and computers. | |||
Latest revision as of 23:10, 21 April 2024
✎ This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.