Here's the schematic:
i would like to find the output impedance of current source IF1 (seen on that rectangle covering a led, T6 and 2 resistors).
Now, i already have the values of IF1,RF2,RF1, Q-points of all transistors and also gains and output/input impedance's of all 3 stages . I believe to be able to solve this problem if i put use the pi-hybrid model but then what?
Would like to add, i also know the base/colector/emitter current of T6