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I am trying to drive the output current Iout but I am not getting what it is shown on the graph. Can you have a look and let me know what I got wrong please? Thanks

enter image description here

here is my attempt enter image description here

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1
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I haven't checked any other calculations other than this:

enter image description here

The two circled expressions are clearly not equal.

But if you simply multiply top and bottom with the same thing, like this: \$ \frac{\beta + 1}{\beta + 1} \$ then you get the expression you are looking for.

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  • \$\begingroup\$ they are correct because it is a current mirror. the emitter current of Q3 is equal to collector current of Q1 + base current of Q1 . \$\endgroup\$ – user65652 Nov 4 '15 at 12:20
  • \$\begingroup\$ One should never assign or reuse a variable name for more than one quantities in the same analysis. It is sloppy and confusing. I now see what you were doing and I believe the printed expression next to the schematic is wrong. \$\endgroup\$ – rioraxe Nov 4 '15 at 19:39

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