The simulation results of second-order Butterworth low-pass filter are inconsistent with the theoretical values (when the frequency is equal to infini

[MHMT+]

The simulation results of second-order Butterworth low-pass filter are shown in the figure. Why can the amplitude only attenuate about 70db in the end? Shoe infinite in theory? Isuldn't it b it a matter of component parameter selection? Where do I modify component parameters?

[tipa]

Привет, M!
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[GGoodwin]

Hi MHMT+,

The simulation results of second-order Butterworth low-pass filter are shown in the figure. Why can the amplitude only attenuate about 70db in the end? Shoe infinite in theory?

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Infinite attenuation can only be achieved at infinite frequency. The "roll-off rate" in the rejection band is almost flat so you might try sweeping up to TeraHertz or maybe even QuettaHertz.

Isuldn't it b it a matter of component parameter selection? Where do I modify component parameters?

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When deviation from expected theoretical results manifest, the parameters of the operational amplifier are the first factors that you should consider. The important parameters are Gain-Bandwidth (Unity Gain Frequency) and Slew Rate rating among others. Click on the operational amplifier and open the Configuration Pane.

Best regards,

G. Goodwin