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I set up an inverting Op-Amp with the following schematic, inputting a 32.8 kHz signal. Two identical resistors on each side of the inverting input. Bias voltage is 7.5 V, Supply voltage is 15 V and 0 V respectively.

enter image description here

I expected an output like this, where the input is near-identical, but 180 degrees out of phase to the output. (This is done with the LTSpice's own near-perfect Op-Amp)

enter image description here

Instead, I got this. I don't know how to describe it with words. Green is the output.

enter image description here

I'm aware that the inadequacies of the LT1490 Op-Amp is a cause in it, but I'm not sure why as the datasheet gives a gain bandwidth product of 200 kHz, which suggests that this Op-Amp should be able to handle operations much less high-speed as 32.8 kHz.

I'd like to solve this problem without getting another type of Op-Amp if possible as my budget is low though I'm open to using other high current, rail to rail op-amps (preferably low-cost with recommendations) if needed.

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The op-amp will never hack a signal that big due to slew rate limiting: -

enter image description here

The op-amp data sheet suggests that it will produce a maximum output voltage change of 60 mV per μs (or, 6 volts in 100 μs). I've drawn that in red on part of your display to show that the op-amp is doing exactly what can be expected of it in a typical situation.

Regarding the jumping around 110 μs, I expect that is an artefact of the model you used (given that the op-amp cannot be expected to change its output anything like that quickly).

You need to choose a proper op-amp that is suitable for a much faster slew rate.

Requests for product recommendations are off-topic (site rules). Read the rules.

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  • \$\begingroup\$ Thank you. By any chance, do you happen to have any rail-to-rail op-amps capable of taking a 15V supply with an output above 20mA? \$\endgroup\$ Mar 23, 2022 at 19:45
  • \$\begingroup\$ I don't have any op-amps. You need to look into the selection charts produced by Farnell, Newark, RS, Digikey and Mouser to name the one I know of. Maybe this one: mouser.co.uk/datasheet/2/609/ADA4522-1_4522-2_4522-4-914641.pdf \$\endgroup\$
    – Andy aka
    Mar 23, 2022 at 20:29

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