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| Inverting vs non-inverting - Pros and Cons |
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| Rerouter:
Been there done that, Op amp noise is calculated using non-inverting math, you don't get a free lunch no matter the architecture, https://www.analog.com/en/analog-dialogue/articles/op-amp-issues-noise-gain.html Instead you have to get creative with what you can alter, |
| Wimberleytech:
--- Quote from: Rerouter on February 13, 2020, 12:00:07 pm ---Been there done that, Op amp noise is calculated using non-inverting math, you don't get a free lunch no matter the architecture, https://www.analog.com/en/analog-dialogue/articles/op-amp-issues-noise-gain.html Instead you have to get creative with what you can alter, --- End quote --- So at first glance the S/N for the inverting configuration would seem to be better (in terms of spectral density). However the BW of the inverting configuration is less (thus less RMS noise after integrating over the BW). In the end, it may be a wash. I would need to do some math to verify this...and it is still kinda early in Texas. |
| pwlps:
Another point to add to the list: stability issues and the role of parasitic capacitances at high frequencies, as discussed here: https://www.researchgate.net/post/Why_are_inverting_op_amp_amplifiers_used_in_most_cases_instead_of_non_inverting_amplifiers |
| Zero999:
The inverting configuration is more stable, than non-inverting, because it has a higher noise gain. An op-amp which is only stable down to a gain of 2, in non-inverting configuration, will be unity gain stable, in the inverting configuration. |
| TimFox:
The main downside to the inverting configuration is noise. For a reasonable input impedance, there is a resistance of that value in series with the input signal, with associated thermal noise. The non-inverting configuration can present lower resistance to the op-amp inputs. One interesting possibility to avoid common-mode problems is to connect a floating source (such as a phono cartridge) between the feedback network and the inverting input, with the non-inverting input grounded. This is rarely done, since it requires a truly floating source. |
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