Difference between BAW-Filter and Quartz Crystal Filter

[highing89]

Hey guys!

I have a question concerning the physical differences of a Baw-Filter and a Quarz Crystal Filter.....

So a quartz crystal Filter works because of the pieo electric effect. A crystal is placed between two electrodes, one at the top and one at the bottem. AC current leads to a displacement of the atoms, the crystal begins to shiver, and a charge can be recognized.


I read a Article aoubt the BAW-Filter (Bulk Acoustic Wave Filter) and I'm a confused because the setting is the same compared to a Quarz crystal filter. There is a piezo Film and here again there are electrodes at the top ad the bottem of the piezo Film.

So whats exactly the difference between a Quarz Crystal Filter and a Bulk Acoustic Wave Filter ? What means exactly the acoustic wave ? Isn't there an Acoustic wave at the Quartz Filter?


Thanks a lot =)

 

[Bob60]

Isn't there an Acoustic wave at the Quartz Filter?

Yes. Also exist SAW filter based on Quartz material. Converting coefficient for
Quartz from electric to acoustic not so big but excellent geometry stability.