Hi kai klaas69,
I hope this message finds you well. I wanted to reach out regarding the Second-order Butterworth Bandpass Filter circuit (kung_tlv9002.TSC) that you assisted me in designing around 7 months ago. You can find the original discussion we had on the TI E2E Amplifiers Forum at this link: https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1207108/tlv170-butterworth-filter
I tested the frequency response by inputting 150mVpp at 1kHz and found that the low-frequency (below 400Hz) in the output waveform were too low, as shown in the diagram below.
If bypassing Bandpass Filter circuit (kung_tlv9002.TSC) . It appears that there is no attenuation.
I tried changing C4 from 10nF to 33nF. The low frequencies passed, but the high frequencies failed.
Please assist in fine-tuning the circuit so that it maintains -3dB or higher at 300Hz.
Thank you!
Kungyeh