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I am designing a universal biquad filter in LTSpice and ASLK Pro board with a square wave input:

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I have taken the Q factor as 1. I'm not convinced it is right. Is it as simple as the ratio of RQ/R6? I verified this in the magnitude response of BS, Q = fc/BW, where I got approximately 0.98.

The problem I am facing is that, when my Q=1, all the resistors are equal, the transient response looks like this, it doesn't complete the full cycle.

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How does this affect the working of a biquad filter? The Bode plot shows a proper working condition and my notch is quite steep at -50 dB.

Why does the notch value reduce as my RQ value increases? Shouldn't it be the notch value increases as my RQ increases?

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I also have another doubt regarding the waveform in the transient analysis. This is at Q=2.91 (verified with Bode, I calculated the BW for fL and fH at -3 dB). Why does the high pass filter have that extra rise? How does this get filtered output in the bandpass integrator?

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The same happens when the value of RQ is 1.61k. There is a rise at the rising edge and it exceeds the square wave input:

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An underdamped response reaches stable state soon, a critical damped response has ringing and takes longer to reach stable state, so which damping is preferred to have in a filter?

I am a student and I am quite new to these topics, please bear with me. It would be super helpful to get a few answers.

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    \$\begingroup\$ I’m voting to close this question because the OP wants a discussion and is asking open-ended questions \$\endgroup\$
    – Andy aka
    Commented Jul 10 at 7:39
  • \$\begingroup\$ "Bode plot" is not a "transient plot". It is obvious that with square wave input, you should have some "rise" in the HPF output ... \$\endgroup\$
    – Antonio51
    Commented Jul 10 at 8:23

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