I am trying to design and simulate a capacitive accelerometer.

The idea is to model the sensor as a capacitance bridge to which an AC signal is inserted. Each arm of the bridge acts as a voltage divider proportional to the acceleration (as capacitance). Then the signals are rectified and summed up to result in a signal proportional to the input. My question is both specific and general. I have no idea how to choose values for the resistors, capacitors and the source of this circuit. And in general what is the design process (choosing values) when designing a read-out circuit of any type of sensor?

I found the circuit on a paper it is not mine.

  • \$\begingroup\$ can this help you? electronics.stackexchange.com/questions/619418/… \$\endgroup\$
    – Antonio51
    May 17, 2022 at 16:29
  • \$\begingroup\$ not really, my main problem is that I don't understand what the capacitors/resistors before the amplifier do \$\endgroup\$
    – GUI
    May 17, 2022 at 18:14
  • \$\begingroup\$ C3-C1 and C4-C2 are 2 capacitive dividers. The two horizontal diodes are peak detectors, one is positive, and the other is negative. The two right two resistors take the mid-point for the amplifier. It is not the very best topology because of the knee of the diodes. \$\endgroup\$
    – Antonio51
    May 19, 2022 at 14:58

1 Answer 1


The design values will be determined by the physical parameters of whatever is making the sensor. Remember that two conductors with distance between them can make a capacitor. So whether this is happening in an integrated I see or you actually have two separate capacitors on an integrated circuit, the values of these can be calculated.

It looks like the last few capacitors and resistors form an RC circuit before a gain stage which gives you time constant for a filter. The first two capacitors need to have enough capacitance to pass AC to the sensor caps and the rest of the circuit


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