Frequency – Do MEMS Accelerometers Have a Lower Frequency Limit?


Being a higher level programmer by education I have no deeper knowledge of electronics and electromechanics, so feel no obligation to answer this.

I'm wondering about MEMS accelerometers. I heard a claim from a coworker the other day that MEMS accelerometers have a lower limit to what acceleration frequencies they can pick up.

Due to the ODR, (Output Data Rate), we have a finite rate at which we receive distinct samples of the measured accelerometer waveform. Usually (or always?), these accelerometers also employ some sort of lowpass-filter. Thus, we have an upper limit of what wave-frequencies we can reconstruct with the data gathered (due to the Nyquist theorem, at most half of the ODR.) This is known.

But is there any lower limit to what frequencies the accelerometer can pick up, at least to an extent that we can isolate and/or reconstruct it?

Intuitively, my best guess is that it can pick up arbitrarily low frequencies, as long as we have a sufficiently high ODR, and there are detectable forces acting on the accelerometer, – I mean, it can pick up static "forces" such as gravity, so why not low or really low frequencies as well?

Best Answer

Capacitive MEMS (yours, probably) and piezo-resistive accelerometers have a DC-response and are almost always DC-coupled, so they can measure down to 0Hz without problems.

Piezo-electric accelerometers, however, are almost always AC-coupled and can't go below a few Hz, and can't measure static acceleration.