How to get accurate 26Meg frequency of collitts oscilator

[kkt51]

I am designing a DCXO block which clock is 26 Meg. But, using crystal model R/L/C parameters showed in picture, I can't get accurate 26Meg value by formula
Here is the process of calculation, I select a set of R/L/C parameters


1.From calucation, error of frequency is about 337ppm. it is too larger for our design spec and it is out of our tune range (+/- 60ppm). why can't get accurate value by formula? how could i get accurate frequecny (26Meg) ?
2. with the crystal model in spectre, it could not get 26Meg frequency too. I use colpitts ocsillator with load capacitance 7.5pF , step=50p,reltol=1e-5

 

[BradtheRad]

You're asking for the result (frequency) to have an accuracy of 8 significant figures.

However your incoming data (component values) have only 3 significant figures.

Your result cannot be more precise than the data you put in.

 

[kkt51]

Hi, BradtheRad,thanks for your responce. These crystal R/L/C parameters is provided by supplier. I think supplier
could not provide the parameters with 8 significant figures. it could be used for calcualting of gain of ocs start up.If we could not get accurate 26Meg frequency by formula,how to get the accurate frequency in design? how to verify the accurate value with SPECTRE simulation?