Difference between BAW-Filter and Quartz Crystal Filter

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 =)

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

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