\[A_v \approx \frac{R_E \parallel R_L}{r_e' + (R_E \parallel R_L)} \qquad Z_{in}\approx R_{B1}\parallel R_{B2}\parallel\left[r_\pi+(\beta+1)(R_E\parallel R_L)\right]\]
\[Z_{out}\approx R_E\parallel\left[r_e'+\frac{R_s\parallel R_{B1}\parallel R_{B2}}{\beta+1}\right]\]
采用中频小信号近似，频率滑块只改变显示周期。