Post Go back to editing

ADXL344 Frequency Response

Hello,

We were planning to use ADXL344 for our needs. It's spec specifies our requirements on both sensitivity, range and ODR.

However, there are no frequency response specs specified for any ODR.

What bothers me is that in the datasheet it says "Bandwidth is the −3 dB frequency and is half the output data rate bandwidth = ODR/2."

If that was true, ADXL344 will suffer from huge aliasing issues. Nyquist theorem states that any frequency component above ODR/2 will be wrapped and can show up as a random frequency. If all the analog+digital filtering is doing is attenuating signal to 3 dB at ODR/2, it will lead to aliasing and will distorted frequency spectrum.

Compared to this if you look at datasheet of ADXL357, it states that digital filter has a bandwidth of ODR/4. Now this makes sense since it allows for roll-off and attenuation at ODR/2 is close to -20 dB by digital filtering alone.

So I suspect that this statement is not true: "Bandwidth is the −3 dB frequency and is half the output data rate bandwidth = ODR/2."

And if possible, can you provide either of the two:

- Frequency response at each ODR;

AND/OR

- Anti-aliasing digital filter passband at each ODR

thanks