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I want to know what is different between voltage reference and virtual ground and can you use both of it as rail-splitter in transimpedance amplifier, if not why.

All I know is Virtual ground chips like TL2426 have an opamp buffer at the output, but the main issue if supply voltage changes the output change too due to voltage divider.

Below part number is connect just for demonstration(actual opamp pn is mcp6v02) enter image description here

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  • \$\begingroup\$ The TL081 opamp will not work when its supply is only 3.3V. Its sales sheet says its minimum supply is 7V (when it barely works) and its datasheet does not show any circuit with a supply that is less than 7.8V. The TL2426 needs its COM pin grounded. \$\endgroup\$ – Audioguru Nov 13 '20 at 1:22
  • \$\begingroup\$ Tl081 is just for demonstration actual opamp is different \$\endgroup\$ – Shahreza Nov 13 '20 at 2:38
  • \$\begingroup\$ That TL2426 has an input, common, and output terminal, no supply terminal. your circuit would make sense if the supply 3.3 was connected to the input, and the output was connected to both the sensor low and the opamp + input. But my datasheet says the TL2426 input range is from 4 to 40 V, so 3.3 won't work. \$\endgroup\$ – electrogas Nov 13 '20 at 6:00
  • \$\begingroup\$ My question can I use voltage reference as rail spliter \$\endgroup\$ – Shahreza Nov 13 '20 at 6:04
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Maybe you can. Some series references can both sink and source substantial current (but 'substantial' may only be 1mA or so) and are guaranteed stable with certain capacitive loads, so they act similarly to a rail splitter.

It's also possible to use a shunt reference if you pass enough current through it that it never has to be called upon to source current. Again, there will be some range of capacitance loading that is guaranteed stable. Violate that and you may have oscillation under some conditions. If the maximum load capacitance is very small so you cannot use normal bypass capacitances, then it may be unsuitable for applications where the virtual ground current can change quickly.

The above is all very general, because there are thousands of different possible reference chips, each of them different.

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  • \$\begingroup\$ I found another chip MCP1501 which capable of sinking and souring 20mA current \$\endgroup\$ – Shahreza Nov 13 '20 at 15:51
  • \$\begingroup\$ Do you think 300pF is adequate supply bypassing for your particular application? \$\endgroup\$ – Spehro Pefhany Nov 13 '20 at 15:53
  • \$\begingroup\$ That kinda low since I am using a switching regulator as voltage source \$\endgroup\$ – Shahreza Nov 13 '20 at 15:58

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