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Crystal Equivalent Circuit - RF Cafe Forums

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Post subject: Crystal Equivalent Circuit Posted: Tue Jul 08, 2008 6:42 pm


Joined: Tue Feb 27, 2007 6:16 am
Posts: 46

I wish to design and simulate a crystal oscillator. I have been having great difficulty obtaining typical crystal equivalent circuit values for whatever frequency.

Can anyone suggest a manufacturer that lists the equivalent circuit values for each of their crystals?

Other than measuring the values, is there an easier way of obtaining typical crystal equivalent circuit values?


Regards, Darcy Randall, Perth, Western Australia


Post subject: Posted: Wed Jul 09, 2008 4:12 am


Joined: Fri Feb 17, 2006 12:07 pm
Posts: 218
Location: London UK
Hi Darcy
you will find the equivalent circuit and much useful data on


Post subject: Posted: Wed Jul 09, 2008 11:40 am


Joined: Tue Jul 08, 2008 7:15 pm
Posts: 11
Location: Boulder Colorado
Hi Darcy,

Most manufacturers will specify Rm (series resistance at resonance), Co (holder capacitance) and of course Fo, so all you really need to complete basic model is either Cm, Lm or Q. Frerking lists the following typical Qs:

200 KHz Fundamental - 18e3
2 MHz Fundamental - 54e3
30 MHz 3rd Overtone - 1e5
90 MHz 5th Overtone - 85e3

Many manufacturers will allow you to specify Cm or Lm, but this is not typically specified on data sheet since it makes little difference for clock oscillator, where most crystals are used, and it would add cost to actually measure it in manufacturing.

Hope this helps.


Post subject: Posted: Wed Jul 09, 2008 6:35 pm


Joined: Tue Feb 27, 2007 6:16 am
Posts: 46
Very Helpful, I have what I need. Cheers

Regards, Darcy Randall, Perth, Western Australia


Post subject: Posted: Thu Jul 10, 2008 3:41 pm

Site Admin

Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Hi Darcy,

Try also Fox Elecctronics:

They have detailed specifications for their crystals and good application notres on their website. I had the sdame problem as you and they helped me a lot.

Good luck!

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