I designed a bandpass filter with a cut-off frequency of 0.1hz and 110khz when I applied a 1khz -20khz sine wave to the input of my band pass filter, I saw oscillations (ringing) at the zero cross points.
(It is obvious that there is a higher frequency harmonic here)
When I do an fft analysis, I see oscillations between 4-5 MHz. Around -40dbV, at a level of approximately 8-10mV.I think one of the filters is producing an oscillation. (I tried with different power supplies. The noise is not coming from the power supply.)What is the solution to this or what is the point I missed? capacitance value selection?
When I did AC sweep in Spice simulations and observe in frequency domain there was no problem, everything was perfect.
maybe capacitance value selection, resistance value selection, pcb design, factors that I cannot foresee or other factors that I do not know theoretically
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first High pass filter (opa192)
order Active High Pass Filter Topology: Sallen-Key Stage Gain:1 Cutoff Frequency:0.1Hz
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lowpass pass filter THP210
Multiple-Feedback Topology 2. order Active Low Pass Filter (Gain:1) fully differential Output Cutoff Frequency:110KHz