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PhysicsTruth

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- Homework Statement
- Analyze qualitatively, the output impedance and the open loop gain of a IC 741 Op-Amp from its internal circuit.

- Relevant Equations
- ##V_{out} = A_{o} ( V_{in1} - V_{in2})##

##A_{o}## is the open loop voltage gain.

Here is the internal circuit of the 741 Op-Amp -

Looking at the output stage, the output impedance seems to be the series combination of ##25 \Omega## and ##50 \Omega##, that is ##75 \Omega##. Is this a qualitative explanation enough to justify the output impedance, or am I wrong somewhere and need to take into account some other impedances as well.

Coming to the open-loop gain, the output Push-Pull amplifier has no voltage gain, only it's achieved at the Darlington pair and the initial input stage emitter followers. How do I go on to claim qualitatively that the open loop gain is significantly high, and nearing infinity?

Looking at the output stage, the output impedance seems to be the series combination of ##25 \Omega## and ##50 \Omega##, that is ##75 \Omega##. Is this a qualitative explanation enough to justify the output impedance, or am I wrong somewhere and need to take into account some other impedances as well.

Coming to the open-loop gain, the output Push-Pull amplifier has no voltage gain, only it's achieved at the Darlington pair and the initial input stage emitter followers. How do I go on to claim qualitatively that the open loop gain is significantly high, and nearing infinity?