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I made the sizing for a folded cascode operational amplifier, which is working well, however when I am trying to implement an instrumentation amplifier in LTspice using the blocks, it does not amplify the signal the right way. This is the schematic which I try to implement:

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This is the output voltage:

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I made the sizing as such: R=R1=100Kohms and R2=17700Kohms, for a gain of 51dB. So for the input I apply a sinewave with 10mV amplitude and a frequency of 34 Hz. So for the above parameters I should get an output of 3.55V, but instead I get a rectangular wave with 1.7V amplitude. Implemented schematic in LTspice. enter image description here

Folded cascode schematic: enter image description here

Output and Input waveforms.

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Thank you for reading and your help, I suppose I made some wrong connections in the schematic.

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    \$\begingroup\$ Test each op-amp block in isolation and see that you get what you require i.e. break the problem down to smaller chunks. And, input a smaller signal until the output is linear i.e. use your imagination to fault-find the problem. \$\endgroup\$
    – Andy aka
    Commented Jan 25 at 8:41
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    \$\begingroup\$ Your power supply has only a range of 3.3V, it is impossible you'll get 3.55V output. \$\endgroup\$
    – Jack Black
    Commented Jan 25 at 9:25
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    \$\begingroup\$ In addition to George Guo's comment, 17.7 M\$\Omega\$ is very large, and may not work with a real op-amp even if it works in simulation. With this resistance, you get very little feedback, and you are almost running your op-amps in open loop. Ideal op-amps have linear open-loop amplification. Real op-amps have very non-linear open-loop amplification, but feedback linearizes the closed loop amplification. The small amount of feedback in your case may not linearize your output very much. \$\endgroup\$
    – Math Keeps Me Busy
    Commented Jan 25 at 12:48

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