# Small signal resistor of emitter in CE voltage amplifier

in such a small signal model of CE circuit. Why "re" ( the small signal resistor of the emitter = VT/IE ) is not represented? However, I've noticed that it is shown in CE amplifier with emitter degeneration and also in CB, but not in CE without emitter degeneration nor CC amplifier circuits!

• @utdlegend Because this time $re$ is hiding inside $r_{\pi}$. As we all know $r_{\pi} = \frac{v_{be}}{i_b} = \frac{\beta}{gm} = (\beta+1)*re$ and $gm = V_T/I_C = \frac{\beta}{(\beta+1)*re}$ – G36 Mar 31 '17 at 19:18