Graphical solution of BJT inverter


I have the following BJT inverter circuit and graphs of its electrical characteristics. I need to graphically find the DC response characteristics of this inverter but I don't know how to proceed.

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Best Answer

You have circuits equations: $$U_1 = R_1I_b+U_{be}\text{ (I)}$$ $$U_2 = U_{ce} = U_n - R_cI_c\text{ (II)}$$ and \$I_c = \beta I_b\$

Use the graph to determinate the value of \$\beta\$ and \$U_{be}\$. you have $$U_2 = U_n-R_c \beta I_b$$ so $$I_b = \frac{U_n-U_2}{\beta R_c}$$

Introduce \$I_b\$ in the equation (I) and you get: \$U_1=f(U_2)\$ with \$U_n\$, \$U_{be}\$ and \$\beta\$ constant.