High frequency in MEMS devices

[MrMuscle]

Hello, I am designing a resonant mems accelerometer. It has a resonating beam. We are actuating it by AC voltage + DC voltage. We are going to actuate it at beam's resonance frequency.

When I search for papers related to previous studies, I encounter resonance frequencies ranging from 20 kHz to 400 kHz.

What is the difference between having 20 kHz or 400 kHz? (Difference between having high and low frequency?)

My hypothesis is that, if you want to have a high frequency mems chip, you need high quality silicon (since it is high speed electronics you need a pure,crystalline material with low amount of atomic defects. )
Thanks for your answers.

 

[Joshy]

I don't know the answer. I was curious and looked into it very briefly.

I saw in a textbook by Rebeiz, that they performed a Fourier transform on d'Alembert's principle and plotted the frequency response with different quality factors of the beam. It looked just like the stuff I saw in a controls class in regards to damping: If the Q factor is too low, then the switching speed is slow; if the Q factor is too high, then the settling time is long. A later piece of that chapter mentions that the quality factor of the beam is determined by many mechanical properties such as pressure and temperature.

If the parameters of your beam is (mostly) fixed, then what would be its Q factor with different resonance frequencies? If the parameters of your beam is still being explored, then what mechanical properties would you need to achieve certain specifications such as switching speed or settling time?

I apologize if I'm being too juvenile for the topic.