parameters extraction of XTAL?

[Jeekoky]

How to extract parameters of XTAL(Crystal) in ADS?

I have measure the impedance--frequency curves of XTAL. But i don't know how to extract Cx,Lx,Rx and C0 by software. I heard that gray-box in ADS can do this. Does it true? I can't find any help about gray-box. By the way, can ic-cap do this job? Thanks for your help.

 

[radiohead]

It is not that difficult although many people think so.

Make two measurements, a wideband around the resonance ferquency and a smallband measurement.

The wideband measurement will give you a good estimate for the parallel parasitic capaticance C0, because this parasitice dominates circuit behaviour there.

Next plot the admittance of the smalband measurement input impedance. Where the reactive part becomes zero, you find that a real part is left. Rx is the inverse of this admittance.

Next you also know what the resonance ferquency is. This relates Lx and Cx through

\[2\pi f_{res} = \frac{1}{{\sqrt {L_x C_x } }}\]

The only thing left is the balance between Lx and Cx. This is defined by Qu of the crystal and can be retrieved from smallband measurement also.

This given you a rough estimate of how you could do it - in an intelligent way.