LSM6DSV16X - What could be the reason for the reduced amplitude on the Z axis above 300 Hz?

[PeterHaso]

Hello,

We tested two sensors on a vibration shaker: LSM6DSV16X and IIS3DWB.

All X, Y, and Z axes were tested on each sensor.

The IIS3DWB was tested up to 2 kHz and behaves correctly. The readings are repeatable at approximately 10 m/s².

The LSM6DSV16X was tested up to 1 kHz. The X and Y axes also showed approximately 10 m/s².
However, the Z axis starts to underestimate the values from 300 Hz upwards, and at 960 Hz it shows only about 4.4 m/s².

We tried different filter settings and configurations. We tested several samples of the sensor.
Nothing improved the results. The Z axis clearly has reduced bandwidth compared to the X and Y axes.

The data is read via the SPI interface.

What could be the reason for the reduced amplitude on the Z axis above 300 Hz?

[PeterHaso]

Hello,

We conducted tests on several other devices from the LSM6 family: LSM6DSO and ISM330. In all of these models, the bandwidth of the Z axis starts to roll off above 300 Hz and drops to about half of its value at 960 Hz sinusoidal vibration. The X and Y axes operate correctly.

So it appears that this may be an inherent characteristic of the entire family. I do not understand why the datasheet specifies a bandwidth of 6.66 kHz without providing a separate value for the Z axis, which seems in practice to be limited to around 1.5 kHz.

Has anyone observed a similar effect? Or does anyone have any idea what else could be checked?

Changing the register configuration does not help, since the register settings affect all three axes equally.

We are currently using the IIS3, which behaves correctly, but unfortunately it has relatively high current consumption of about 1.2 mA.