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Clock Source - Crystal Oscillator Example

(Not examinable for part II CST.)

Most electronic products use a soundwave inside a quartz crystal as a clock source.

Ultra cheap products, like a musical greetings card, will use an R/C oscillator, but this will have typically only a 10 percent initial accuracy - (one semitone is 6 percent).

For above 20 MHz or so, the crystal cannot be cut thinly enough, so overtones or PLL multipliers are used.

47: (C) 2008-17, DJ Greaves, University of Cambridge, Computer Laboratory.