\[I_D=I_{DSS}\left(1-\frac{V_{GS}}{V_P}\right)^2\;(\text{JFET饱和区})\qquad I_D=k_n(V_{GS}-V_{TH})^2\;(\text{MOS饱和区})\]
\[A_v\approx-g_mR_D\;(R_S\text{已旁路})\qquad A_v\approx-\frac{g_mR_D}{1+g_mR_S}\;(R_S\text{未旁路})\]
\[Z_{in}\approx R_G\;(\text{JFET自偏置})\qquad Z_{in}\approx R_{G1}\parallel R_{G2}\;(\text{MOS分压偏置})\]
采用中频近似，忽略 \(r_o\)；频率滑块只改变显示周期。