Q.For the CE amplifier circuit using Germanium transistor given below, find i) $r_e^1$, ii) $A_V$, iii) $V_0$, iv) $A_i$, v) $A_p$, vi) $G_p$ Given $I_E$ =1.043mA and $\beta$ =100.

For this germanium CE stage use $r_e' = 52\,\text{mV}/I_E$; the voltage gain is $A_V = Z_0/r_e'$ with $Z_0 = R_C$ (no external load), the output is $A_V$ times the 10 mV input, the current gain is $\beta$ and the power gain $A_P = A_i A_V$. …

[!TLDR]

With the germanium $r_e' = 49.86\,\Omega$: voltage gain 44.12, output 0.4412 V, current gain 100, power gain 4412 (36.45 dB).

This is a small-signal CE analysis using the $r_e'$ model. Because the transistor is germanium, the thermal voltage is 52 mV, so $r_e' = 52\,\text{mV}/I_E$. With no external load drawn, the output impedance is just the collector resistor $R_C$.

Given: germanium transistor, $I_E = 1.043\,\text{mA}$, $\beta = 100$, $R_C = 2.2\,\text{k}\Omega$, input $V_{in} = 10\,\text{mV}$.

i) AC resistance of the emitter diode (germanium):

ii) Voltage gain (with $Z_0 = R_C = 2.2\,\text{k}\Omega$):

iii) Output voltage: …