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I want to design an IEPE sensor signal conditioner. This signal conditioner that I will design will not include gain and attenuator parts. The signal from the IEPE sensor will pass through the coupling capacitor and then pass through the low pass filter (gain :1. After filtering the signal, this low pass filter will convert the single-ended signal to a differential output signal and give it to the ADC input.

When I make the configuration in the picture and apply a 10 kHz ±1 V signal, I can get a differential signal with a slight phase shift.

enter image description here

enter image description here


However, when I put a coupling capacitor at the beginning and add 12 volt DC offset to the AC signal, it does not filter the offset (hp filter with coupling cap) and I get a result like this:

enter image description here

enter image description here

I'm having a hard time understanding where my mistake is. Any idea?

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1 Answer 1

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I'm having a hard time understanding where my mistake is. Any idea?

At the instant the simulation starts it sees a signal and a 12 volt step transient. After some time (milliseconds maybe) this will settle down and the 12 volt transient will subside so, run the simulation for a lot longer and observe the result. Your 2nd graph is impossible to read BTW but, it does show faint signs (over the microsecond time-base) of the outputs rising a little.

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  • \$\begingroup\$ Thanks for your answer Andy, I extended the simulation to 100ms but I don't see any different results. \$\endgroup\$
    – Electronx
    Nov 21, 2023 at 21:16

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