If you need a stable frequency source, the best bet is a crystal, right? The correct answer is a resounding "maybe." It turns out, there are lots of reasons to abandon the tried and true. Traditional clocks involve crystals, modules and ceramic resonators. These components boast excellent accuracy and stability, but because they are mechanical devices, they are less robust than solid-state solutions. Not only are crystals subject to mechanical wear-out, but also physical impact will induce errors in the output frequency and phase. And because they rely on a tuned circuit with a matched driver, they don't always start up as planned or oscillate at the intended frequency. In addition, crystals are not adjustable, and generating multiple frequencies means stocking multiple crystal values.
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