u/Comprehensive-Use986

Hello All,

I was working on BJT based Opamps, and came across NE5532 - which has a very good output resistance in its datasheet - which I think is why this IC is so frequently used in Audio Applications.

I was trying to calculate the Output Resistance/Impedance for the output structure of NE5532, but it doesn't look to be quite direct.

Does anyone know what this impedance actually depends upon?? My expression is currently dependent on the gm, ro, and rpis of Q1, Q2, and Q3 currently