From the OPA140 datasheet here: https://www.ti.com/lit/gpn/opa2140
How do you read this graph? Because on the Y-axis the units are all weird and the numbers are strangely negative.
The open loop gain is listed as:
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2\$\begingroup\$ Look here e2e.ti.com/support/amplifiers-group/amplifiers/f/… \$\endgroup\$– G36Jun 2 at 19:43
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\$\begingroup\$ @G36 Why is there are those gains negative though? There seems to be a difference in between this graph and the one in the link. The one in the link says it is normalized but I don't think that's the case with this one since you can see it doesn't pass through zero at 25C. It's almost like this graph is plotting the actual gain, not the change in gain. \$\endgroup\$– DKNguyenJun 2 at 19:54
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\$\begingroup\$ Aol of an inverting amplifier. \$\endgroup\$– G36Jun 2 at 19:59
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1\$\begingroup\$ @G36 Is that the context? That seems kind of strange to me though since it's supposed to be open loop gain. \$\endgroup\$– DKNguyenJun 2 at 20:10
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1 Answer
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Looks like they’re stating it as the reciprocal, so 0 would be infinite gain. So for a 10k load and 25 degrees C the 1/gain is typically about 0.15u/V or a gain of 6.7x10^6.
That’s 136dB which is quite a bit higher than the typical figure of 126dB over a wide common-mode voltage range.
Not sure why they’re stating it as negative, maybe aesthetics so up=positive, either polarity is okay- it depends on which input they are assuming to be connected to the signal input.
answered Jun 2 at 20:01
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\$\begingroup\$ Yeah that's what I would have surmised too except the negative sign is throwing that all off. \$\endgroup\$– DKNguyenJun 2 at 20:10