The circuit in Figure P12.57 is the ac equivalent circuit of a series-series feedback amplifier. Assume that the bias circuit, which is not shown, results in quiescent collector currents of \(I_{C 1}=0.5 \mathrm{~mA}, I_{C 2}=1 \mathrm{~mA}\), and \(I_{C 3}=\) \(2 \mathrm{~mA}\). Assume transistor parameters of \(h_{F E}=120\) and \(r_{o}=\infty\). Determine the transconductance transfer function \(A_{g f}=I_{o} / V_{s}\).

Rc1=5kQ ww Rc2=3 2 Rc3=1 1 kQ Vs Q2 23 REI=0.1 KQ Figure P12.57 www Rp = 0.8 k RE2 = 0.1 KQ