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The most common solution to provide positive and negative voltage to supply an OP-amp would be to use a voltage divider and another OP-amp. In this way the voltage "on the top" of the voltage divider would be the positive voltage, ground would be negative voltage and the voltage in between would be our virtual ground.

When working with audio-applications it is very important that these circuits do not create noise, so my question is: How do you design these to make sure they don't create noise? What OP-amp should you use?

Virtual ground-circuit

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  • \$\begingroup\$ Welcome to EE.SE! Please insert your bulk capacitors between Positive/Negative and Virtual_Gnd and inject whatever noise you want into the opamp and report back your resulting noise on either rail. \$\endgroup\$
    – winny
    Oct 24, 2020 at 15:26
  • \$\begingroup\$ Creating no noise is not possible (except perhaps at 0 Kelvin). It's tot about that and it's not about choosing the right opamp ... at this stage. It's about understanding your noise budget and designing the circuit to meet that. \$\endgroup\$
    – user16324
    Oct 24, 2020 at 16:22
  • \$\begingroup\$ user, an opamp usually makes a terrible bipolar supply from a single-ended power source. Their output current compliance is negligible compared to the need in most audio applications. Assuming I gathered your goal correctly, anyway. \$\endgroup\$
    – jonk
    Oct 24, 2020 at 17:23

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All power supplies that are isolated from the power line will have some form of transformer.

There will be capacitance between primary and secondary of that transformer.

There will be "displacement current" coupled across that transformer.

That current will explore all possible paths, to return to the source of the charge.

Switching power supplies will produce 100 nanosecond edges (if not faster), and your opamp needs to harness that energy.

Or you must use bypass capacitors.

Otherwise ugly "ground loops" form, as that transformer-provided current makes its way back to the source.

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