Maddca
commented
2 years ago Discovered that the problem wasn't necessarily the noise, removing the potential ground loops caused no significant changes. Instead the problem turned out to be caused by shorting the bandpass filter in the beginning, which we had done because of a faulty connection with the inductor. We needed to short it with a capacitor instead of a wire since using a wire caused the resistor in the frequency generator to be in parallel with one of our dc offset resistors essentially causing us to lose our dc offset entirely.
Despite fairly low noise on the low pass amplifier simulations, we're getting way higher noise levels than simulations predicted. Possible solutions include increasing gain, switching to a lower noise op amp, and finding and eliminating other sources of noise. The noise on the output is around 10uV and the simulations show values of 1-2uV, depending on the version.