写在开始

最近又花了一点时间去听了一阵子的模电,这里把之前听的那些的笔记搬上来,表示应该并没有搬完,所以之后还会继续发

三极管放大电路

动态值

$$ \begin{equation} \begin{aligned} A_u &= A_{u1} \cdot A_{u2} \\ A_{u1} &= - \frac{\beta_1 R'_{L1}}{r_{be1}} \\ R'_{L1} &= R_{C1} \| r_{i2} \\ r_{i2} &= R_{n2} \| r_{be2} \\ A_{u2} &= \frac{- \beta_2 R'_{L2}}{r_{be2}} \\ R'_{L2} &= R_{C2} R_{be2} \\ r_i &= r_{i1} = R_{b1} \| r_{be1} \\ r_0 &= R_{C2} \\ r_{be} &= r'_{bb} + (H \beta) \frac{\alpha \sigma}{Z_{eQ}} \end{aligned} \end{equation} $$

重要的公式一共有三个

$$ \begin{equation} \begin{aligned} A_u &= A_{u1} \cdot A_{u2} \\ r_i &= r_{i1} = R_{b1} \| r_{be1} \\ r_0 &= R_{C2} \\ \end{aligned} \end{equation} $$

共射极

$$ \begin{equation} \begin{aligned} A_u &= \frac{-\beta R'_L}{r_be + ( 1 + \beta ) R_e } (R_e 可能为0) \\ r_i &= R_b \| [r_{be} + ( 1 + \beta ) R_e] \\ r_0 &= R_C \end{aligned} \end{equation} $$

共集极

$$ \begin{equation} \begin{aligned} A_u &= 1 (约等于1) \\ r_i &= R_B \| [r_{be} + ( 1 + \beta ) R'_e] \\ R'_e &= R_e \| R_L \\ r_0 &= \frac{R'_s + r_{be}}{1 + \beta} \\ R'_S &= R_s \| R_b \\ \end{aligned} \end{equation} $$

关键公式也是三个

$$ \begin{equation} \begin{aligned} A_u &= 1 (约等于1) \\ r_i &= R_B \| [r_{be} + ( 1 + \beta ) R'_e] \\ r_0 &= \frac{R'_s + r_{be}}{1 + \beta} \\ \end{aligned} \end{equation} $$

MOSFET

mos管有分n沟道和p沟道,n沟道对应的是普通三极管的NPN,p沟道对应的是PNP

$$ \begin{equation} \begin{aligned} I_g &= 0 \\ i_g &= 0 \end{aligned} \end{equation} $$

栅极没电流