I am simulating the use of a tl074 quad op-amp and i have configured one of the op-amps as a non-inverting op-amp, where R1=1 Meg and R2=4 Meg and the supply voltage is 9V. Every time i put a signal in, the output is always offset negatively. Is this how the op-amp is supposed to work? or are there more components to add to get just an amplified signal rather than a negatively offset amplified signal? This is basically the configuration i used below.


simulate this circuit – Schematic created using CircuitLab

This is the signal output that i get, Green being the input. Blue being the output. enter image description here Sorry if my terminology is wrong. Ill gladly fix my terminology if it is wrong.

  • \$\begingroup\$ Your text talks about R1 and R2, but your schematic shows Rs, Rf, and Rin. Please fix one or the other so that it's clear which resistor in the schematic you mean when you mention it in the text. \$\endgroup\$
    – The Photon
    Apr 25 '19 at 22:42
  • \$\begingroup\$ Also, what do you mean by "offset negatively"? Give an example of an input, what output you expected, and what you actually got. \$\endgroup\$
    – The Photon
    Apr 25 '19 at 22:43
  • \$\begingroup\$ Now your text says you configured a non-inverting amplifier, but your schematic shows an inverting amplifier. Please make clear what was your actual circuit configuration. \$\endgroup\$
    – The Photon
    Apr 25 '19 at 22:44
  • 1
    \$\begingroup\$ @ForeverLearningJP Take a look at the datasheet to find the bias currents for the opamp (may as well look at the offset current while you are at it.) Then compare these current magnitudes with the magnitudes of your resistors. What kind of voltage drop might be present? I've not looked. I just want to know if you've considered that factor. \$\endgroup\$
    – jonk
    Apr 25 '19 at 22:56
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    \$\begingroup\$ "The Circuit I provided is the same circuit that I have on ltspice which gave me that output." - I reproduced your circuit in LTSpice and the output was (as expected) an almost constant +1.61V. What model were you using for the TL072? \$\endgroup\$ Apr 27 '19 at 4:16

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