In the circuit below, the BJT is biased with a constant-current source,
and $v_{sig}$ is a small sine-wave signal. Assume $\beta=100$, $V_T=25$ mV, and neglect the Early effect.
(a) Find $R_{in}$. (5 pts) (b) Find the gain $v_o/v_{sig}$. (5 pts)
+3 V
20 k$\Omega$
20 k$\Omega$
200 k$\Omega$
250 $\Omega$
$R_{in}$
CE Amp
w $R_e$
20 k$\Omega$
$R_{in}$
200
$R_{in}$ =
