0

I have currently understood how to calculate capacitors C1 and C2 needed to be connected to a crystal to make its frequency stable in pierce oscillators. Regarding the following equation, C1 and C2 are calculated: C1=C2=2*Cload-2*Cstray Cload (load capacitance) can be extracted from the datasheet of the crystal, however the Cstray can not be measured exactly. This made me ask you, how much will slight variations of c1 and c2 can affect the crystal frequency in room temperature? I make an example, How much do I lose accuracy in a 8MHz pierce oscillator, if I choose 20pF ones, while I should implement 10pF ones.

Bornak
  • 85
  • 7
  • You can model this quite easily if you have the equivalent model of the crystal. Try all these answers in order to get greater understanding: [Ans 1](https://electronics.stackexchange.com/questions/413054/confusing-quartz-crystal-impedance-graphs), [Ans 2](https://electronics.stackexchange.com/questions/320059/different-15-and-10-pf-load-capacitors-on-32-768-hz-quartz-crystal) and [Ans 3](https://electronics.stackexchange.com/questions/98838/designing-an-oscillator) – Andy aka Feb 18 '20 at 11:54
  • Thank you andy aka, where can I find the equivalent model of a crystal? These parameters are not mentioned in datasheet. – Bornak Feb 18 '20 at 16:33
  • Many crystal suppliers do provide this information so they are probably having this information on their website. Provide a link in case you missed something in the data sheet. – Andy aka Feb 18 '20 at 16:35
  • How much will be the frequency range of the oscillaror with unexact load capacitors mentioned above? I need only an approximation to get a general insight on this issue. – Bornak Feb 18 '20 at 16:38
  • It's impossible for me to say - I'd use a simulator and model and get a precise answer. – Andy aka Feb 18 '20 at 16:39
  • Could you please clarify it for me, how to extract following crystal equivalent circuit?https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.farnell.com/datasheets/321153.pdf&ved=2ahUKEwjAs8qMx9vnAhUvQRUIHUCkBHwQFjABegQIAhAB&usg=AOvVaw0fUUFx7tC4IPEM1nTcHVPd&cshid=1582044786140 – Bornak Feb 18 '20 at 16:55
  • Multicomp are not the original manufacturer (They badge engineer) so try finding an equivalent crystal from an actual manufacturer. – Andy aka Feb 18 '20 at 17:10

0 Answers0