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The single-ended to differential converter on the right side works fine in sim only if I set opamp rails Vcc=12V and Vee=-12V as split supply. But if I supply the circuit by using 24V supply and a buffered virtual ground circuit as below it doesn't work:

enter image description here

I found the example usage of the BUF634 here: enter image description here

What can be the problem?

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closed as unclear what you're asking by PlasmaHH, PeterJ, Dmitry Grigoryev, Dave Tweed Sep 30 '17 at 11:43

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ Define "doesn't works" with results on all pertinent nodes. You ought to know better by now. \$\endgroup\$ – Sunnyskyguy EE75 Sep 27 '17 at 0:43
  • \$\begingroup\$ @TonyStewart.EEsince'75 I get nonsense output from the converter if I use that virtual gnd circuit. Am I wiring it wrong? \$\endgroup\$ – HelpMee Sep 27 '17 at 0:48
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    \$\begingroup\$ "nonsense output" is not much of an engineering term. Try again. Describe what you actually see using actual engineering terminology. \$\endgroup\$ – brhans Sep 27 '17 at 1:09
  • \$\begingroup\$ simulate and see, otherwise i have to upload plots and have to leave home now. I use LTspice \$\endgroup\$ – HelpMee Sep 27 '17 at 1:13
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    \$\begingroup\$ The BUF634 is a high-current, high-frequency device. I somehow doubt that you are using good ground (preferably ground plane) construction, and your schematic shows no decoupling - that 220 uF doesn't count. \$\endgroup\$ – WhatRoughBeast Sep 27 '17 at 1:15
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NO idea what you mean by doesn't work.. Works fine here..

schematic

simulate this circuit – Schematic created using CircuitLab

enter image description here

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  • \$\begingroup\$ Thanks adding those 100nF C2 and C3 solved the problem. Do I need C4 in my case where I use a BUF634? \$\endgroup\$ – HelpMee Sep 28 '17 at 1:25
  • \$\begingroup\$ my circuit works fine. just having 200mV ripples at Vcc rails. If I use 100 Ohm and 100u as LP filter on rails it mitigates, but 100u is a bit too much, \$\endgroup\$ – HelpMee Sep 28 '17 at 1:37
  • \$\begingroup\$ @doncarlos where is the ripple coming from... the supply itself? ANyways, more caps... \$\endgroup\$ – Trevor_G Sep 28 '17 at 13:38
  • \$\begingroup\$ Ripples are originating from BUF634, and appearing at Vcc and Vee \$\endgroup\$ – HelpMee Sep 28 '17 at 17:15

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