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So I'm simulating a switched capacitor filter using LTC in mode 3. Here is my schematics:

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Now I'm performing a transient analysis with a 3V sinusoidal voltage with frequency 1.4 kHz and a 3V square wave with frequency 250 Hz. However I don't understand my results. The sinusoidal one is way off, while the square wave is while more acceptable I don't get what is going wrong. Can someone please help me understand this? My results:

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  • \$\begingroup\$ Your circuit has gain and the output is hitting the limits it can produce. Try lowering your input signal amplitude. \$\endgroup\$
    – Andy aka
    Nov 27, 2020 at 17:51

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Take a look at the datasheet for guidance. The output is only specified to sink 3mA, and you're limiting at about 3V above the negative rail, into a 1\$\mathrm{k}\Omega\$ resistor. In other words, you're limiting at the point where the output is asked to sink 3mA.

Try resizing resistors as necessary so that the output resistors are no less than 5\$\mathrm{k}\Omega\$ (the data sheet implies that 5\$\mathrm{k}\Omega\$ is the lowest "good" value to use -- I'd consider 10\$\mathrm{k}\Omega\$ or more).

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