Virtual ground topology

I recently saw a single supply opamp circuit that had what looked like an interesting virtual ground topology.

The incoming signal needed to be differential for the rest of the circuit, so there's an opamp phase splitter arranged with a voltage divider on one of the noninvering inputs such that the outputs of the phase splitter center at half the supply at quiescense. Equal value resistors are then taken from each op amp output of the phase splitter and the non inverting input of another opamp configured as a unity gain buffer is connected there. That amp's output is then used as the virtual ground for the system.

I guess this arrangement saves using an electrolytic bypass cap across the virtual ground voltage divider at the cost of an opamp section. I haven't simulated this yet as I'm mobile right now; I wonder if there could be issues with this arrangement, like startup problems? Thanks.

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If you think about this, you really aren't saving a filter cap. [Well unless your intent was just a voltage divider with cap and not a buffered virtual ground.] You could have just as well created a virtual ground and not plop a cap on the output. It just wouldn't be as good when the op amp creating the virtual ground runs out of loop gain.

If your signal is differential, why do you need a virtual ground? You process the signal with fully differential circuits, the outputs of which are kept centered around a suitable voltage with common mode feedback.

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are you talking about the so called FDA fully differential amps?

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Sounds like a single-ended to differential conversion for twisted pair cable driver and CM drives the shield.

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circuit diagram needed


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