\[A_v = \frac{R_C}{r_e'} > 0 \;\text{(同相)} \qquad Z_{in} = r_e' \parallel R_E \approx r_e' \;\text{(极低!)} \qquad Z_{out} \approx R_C\]
\[r_e' = \frac{V_T}{I_C} \approx \frac{26\text{mV}}{I_C} \qquad V_{CB}=V_C-V_B=V_{CC}-I_CR_C-(V_E+V_{BE})\]
采用中频小信号近似，频率滑块只改变显示周期。