I know it is small - but why? I thought it is linked to stage 3 gain, but I thought as a current limiter, it will add to output impedance?

Thanks in advance

 

Idealy the output impediance is zero. You should take a look at the internal circuity of an op amp to see this.

 

The output resistance of an opamp is about 50 ohms to 200 ohms.
But since it is almost always used with negative feedback then its output impedance at low frequencies is very close to zero ohms.

If a load tries to change the output voltage then the negative feedback will cause the output voltage to cancel the change by the load.

The text in the link is WRONG!

 

I know it is small - but why? I thought it is linked to stage 3 gain, but I thought as a current limiter, it will add to output impedance?

Thanks in advance

What do you mean by "stage 3 gain" and to what "current limiter" do you refer?

 

Yes, opamps have an output current limiter that is usually not operating.