Hi integrate two BMX160 in our design, one in a main board to act as magnetometer and one in a second board to act as accelerometer. I do two different PCB layout, without diffuse plain below the one on the main and with diffuse GND and Supply plain on the second board. Both board are 4 layer 1.6 mm thickness. The test results on the magnetometer are very different, completely out of specification the one on the main, more of 60° degree of error on angles around 100°N, and close to the specification the one on the second board. I did not find any specification regarding the PCB layout, presence, size and distance from diffuse copper plane below the IC. Can You share the reference that has been used to qualify it and needed to meet the specification.
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