I see some data sheets of some saw resonators with a nominal frequency at the GHz range, whereas normal AT quartz cuts are limited to some hundreds of MHz.
What is really the difference here, especially in terms of frequency stability and precision?
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3\$\begingroup\$ Why not make it easier for us and supply links to those datasheets. Besides that, what you ask should also be listed in those same datasheets. \$\endgroup\$Bimpelrekkie– Bimpelrekkie2016-02-29 14:11:56 +00:00Commented Feb 29, 2016 at 14:11
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2 Answers
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The 'simple' answer to this is: a resonator is much less stable than a crystal. In terms, they are also less precise (look a the tolerance on the datasheets).
Long geeky answer:
The external ceramic resonator is less expensive, and less accurate than an external crystal. It is usually a 3 wire device, the third lead going to ground.
An external crystal is more accurate than a resonator. It requires two, identical, external capacitors tied to ground. They are more expensive than resonators. They come is a wide range of accuracies.
If you are more a list person:
Resonators:
- not that sensitive component
- smaller
- less accurate (say, 0.1%-1.0%)
- cheaper
- may have internal capacitors or need external ones
- good for low speed serial port comms
- better ESD tolerance
- better shock/vibration tolerance
- not very suitable for a RTC/timekeeping/wall clock
crystals:
- quite sensitive component
- bigger
- more accurate (10ppm-1000ppm)
- more expensive
- needs external capacitors, their value depend on what crystal is designed to work with
- does not like ESD
- does not like shock/vibration
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\$\begingroup\$ Fixed. Sorry, was thinking some older tech as well as typical resonators vs saw. List should be accurate now. It's also hard to determine a lot without seeing the data sheets. \$\endgroup\$biggi_– biggi_2016-02-29 15:13:40 +00:00Commented Feb 29, 2016 at 15:13
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As the questioner mentions the frequency ranges a very different. They are two different types of piezoelectric resonators, typically using quartz. Classic AT-cut quartz crystals have frequency inversely proportional to thickness, which limits the upper frequency range. The temp stability can be +/10 ppm 0 to 70C in even a cheap crystal. SAW technology, used more for filters than resonators, use interdigitated metal fingers on a quartz surface, frequency inversely proportional to finger spacing. That sets the lower frequency limit to devices of practical size. In their respective ranges SAW and crystal based oscillators can have outstanding low noise performance.
