Finding Voltage Gain in Common Collector Configuration Without RE

[erece]

Homework Statement

for the common collector configuration shown i need to find the voltage gain.
The voltage gain formula is A_V = (β+1)(r_oll R_E)/(r_π+(β+1)(r_oll R_E)
But in the circuit R_E is absent . So how do we consider it ??
Nothing is given about the current source.

from the circuit theory i know that the internal impedance of a current source is very high (am i correct ?).

So in this case how do we relate it ?

Homework Equations

The Attempt at a Solution

 

[CWatters]

Yes the impedance of an ideal current source is infinite.

 

[aralbrec]

from the circuit theory i know that the internal impedance of a current source is very high (am i correct ?).

Since resistance attached to the output of the transistor is infinite you can't ignore the output resistance of the transistor itself. You've no doubt been ignoring it in most of your circuits but this could only be done because Ro (of the transistor) >> than anything attached to the transistor output and it was connected in parallel to anything attached at the output.