written 3.5 years ago by |
Assuming $\beta=100$
$\mathrm{R_B=R_1||R_2}$
$\mathrm{R_B=\dfrac{15\times10^3\times5\times10^3}{15\times10^3+5\times10^3}}$
$\mathrm{R_B=3.75\ K\Omega}$
$\mathrm{V_{TH}=V_B=V_{CC}\times\dfrac{R_2}{R_1+R_2}}$
$\mathrm{V_B=20\times\dfrac{5\times10^3}{15\times10^3+5\times10^3}}$
$\mathrm{V_B=5\ V}$
Applying KVL to the Base - Emitter Loop
$\mathrm{V_B-I_BR_B-V_{BE}-I_ER_E}=0$
But, $\mathrm{I_E=\big(1+\beta\big)I_B}$
$\mathrm{V_B-V_{BE}-I_B\Big[R_B+\big(1+\beta\big)R_E\Big]}=0$
$\mathrm{I_B=\dfrac{V_B-V_{BE}}{R_B+\big(1+\beta\big)R_E}}$
$\mathrm{I_B}=\dfrac{5-0.7}{3750+\big(1+100\big)3000}$
$\mathrm{I_B=14.01\ \mu A}$
$\mathrm{I_C=\beta I_B}$
$\mathrm{I_C=100\times62.91\times10^{-6}}$
$\underline{\underline{\mathrm{I_C=1.4\ mA}}}$
$\mathrm{I_C\approx I_E}$
Applying KVL to Collector - Emitter Loop
$\mathrm{V_{CC}-I_CR_C-V_{CE}-I_CR_E}=0$
$\mathrm{V_{CE}=V_{CC}-I_C\big(R_C+R_E\big)}$
$\mathrm{V_{CE}}=20-1.4\times10^{-3}\big(2\times10^3+3\times10^3\big)$
$\underline{\underline{V_{CE}=13\ V}}$