MP23DB02MM Frequency Range

[JKing.3]

I interested in the higher frequency range of this device. The datasheet states clearly the LF cutoff at 35Hz, but there is no real discussion on the HF end apart from the characteristic graphs stopping at 10KHz. The device can be clocked up to 3.3MHz so it would seem that there is scope for higher frequencies. Is there any characteristics or design information for going above 10KHz and what are the tradeoffs? I see from some other posts that SNR is affected as the clock frequency increases.

Any guidance appreciated.

Thanks

Julian 

[Peter BENSCH]

Well, the generic type of a microphone is typically intended either for speech or for high frequencies such as ultrasound. The typical range of speech is approximately between 200Hz and 2kHz, so the 10kHz mentioned in the data sheet already extends this limit quite well upwards. You can also process up to 20kHz with the microphone. At higher frequencies, the internal filter function becomes effective due to internal digitization.

If higher frequencies such as the ultrasound mentioned above are to be processed, a suitable MEMS microphone with an analog interface, i.e. without the digital interface, must be used, which then also requires analog processing, e.g. the IMP23ABSU.

Hope that helps?

Regards
/Peter

[Federica Bossi]

Hi @JKing.3 ,

The maximum frequency you can acquire is 20kHz by design.

[JKing.3]

Thank you for your reply Peter. I was hoping I might stretch the microphone to the frequencies we need, which is 25 & 33KHz, but looks like we'll have to go analogue.

Regards

Julian

[JKing.3]

Hi Freerica,

What happens above 20KHz, is there a predictable roll off or something less predictable.

Thanks

Julian

[Federica Bossi]

Hi @JKing.3 ,

There is a sensitivity rolloff that depends on the gasket in which the microphone is mounted (https://www.st.com/resource/en/application_note/an4427-gasket-design-for-optimal-acoustic-performance-in-mems-microphones-stmicroelectronics.pdf)