PDM Mems Microphones - how fast can they be clocked?

[ralphrmartin]

I want to use a (PDM) mems microphone for some ultrasonic work. None of the datasheets seems to indicate what maximum clock frequency can be used for these devices. Can anyone give me any idea? Typically they are used at a few MHz. Can they be pushed to 10 or even 20 MHz - or more?

Please let's not get side-tracked into a discussion of the frequency responses of these devices (some mems devices do target ultrasonics), attenuation in air, etc. Those issues are secondary...

Thanks!