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?


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

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    \$\begingroup\$ Define "doesn't works" with results on all pertinent nodes. You ought to know better by now. \$\endgroup\$ – Tony Stewart 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

NO idea what you mean by doesn't work.. Works fine here..


simulate this circuit – Schematic created using CircuitLab

enter image description here

  • \$\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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