op amp differentiator in LTSpice

Thread Starter

boablahuj

Joined Mar 3, 2016
14
Hello. I've designed differentiator scheme in LTSpice and for some reason it's not working properly. Values are okay I think, I would love to know what am I doing wrong, since I'm trying to get this to work for few hours now. Phase is completly wrong on the output and I'm not sure if capacitor C1 is needed. My scheme:

This yellow box is op amp, 1 - non-inverting input, 2 - inverting input, 3 and 4 +/- power supply and 5 - output.
 

Thread Starter

boablahuj

Joined Mar 3, 2016
14
I imported PSPice model and used it few times already, every time it worked perfectly.
And that's the output I want to see:

i have fixed parameters: Uinput = 4V, Uoutput = 2, frequency = 5kHz. I could choose R, so I went with 10k, and then calculated C = 2.5nF and R1 << 1273 ohms, so I choose 100 ohms for now (No values form E24 series for now).
 

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Thread Starter

boablahuj

Joined Mar 3, 2016
14
Results of your simulation are similiar to mine, so it turns out my sim is okay. I was worried because of the phase shift, but my teacher said it's done properly. Thanks a lot for all feedback!
 
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