AVR-Chat

> i am looking for a precise SMT crystal that has temperature
> compensation feature ... anyone have seen such product in the internet?
> i had searched dozens of crystal manufacturers but i didnt see one.
> i dont know if such product really exist.
> most crystals available have -0.03 to -0.04 PPM/C^2(degree celcius
> squared) at -40C to 85C temperature range.


Precision oscillator design is somewhat of an art.
You'll need more than just a stable crystal.
Getting the crystal isn't that hard, just email Statek, or one of the
others, and tell them your requirements. They can do customs.

The rest of the circuit will need to be designed though.. The caps and
resistors selected to match the crystal, and the rest.

For example, I have a couple of repeaters that use crystals to determine
transmit and receive frequency. They do NOT use any ovens, the whole thing
draws less than 30mA on standby  :)    But the oscillator circuits have
seven thermistors, and are quite complicated.
5ppm -40C to +60C is guaranteed. It's the sort of thing that you typically
helicopter to the peak of a mountain and leave for a few years.


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