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ADXL001 RC filter for low noise

Question asked by avalles on Apr 16, 2015
Latest reply on Apr 21, 2015 by venkat

We are trying the ADXL001-70 MEMS sensor using one EVAL-ADXL001. We would like to measure vibration between 0 and 5 Khz . We have placed 1k/33nF (4.8 Khz) FC filter. We supplied the board with different power supplies between 5 and 6 V.

Without vibration the less noise measurement is got when we use a battery of 5 V as power supply. But however there is 34 mV between peaks. With a RC filter for 1.6 Khz (1k, 100nF) this value is 20 mV, that is almost 1 g.

We have glued the eval board on one handled shacked of pcb (394C06: 159.2 Hz 1g RMS), but the results that we observe in the oscilloscope aren’t so good as we need. The frequency is correct (around 159.2 Hz and the amplitude also around 35 mV = 24.2 *1.41à 1 g * 1.41). But there are many noise.

Is there any other RC combination to get better measurements between 0 and 5 Khz? Is there another detail that we didn’t take into account?