The input resistance of a common emitter transistor amplifier, if the output resistance is 500 kΩ, the current gain α = 0.98 and power gain is 6.0625 × 106, is

Question

The input resistance of a common emitter transistor amplifier, if the output resistance is 500 kΩ, the current gain α = 0.98 and power gain is 6.0625 × 106, is (A) 198 Ω (B) 300Ω (C) 100Ω (D) 400Ω

Tardigrade Admin · Accepted Answer

Voltage gain= AV =β (R2/R1) Also,current gain β =(α/1-α) =(0.98/1-0.98)=49 AV =(49) [(500 × 103/R1)] Power gain =6.0625 × 106 =49 × [(500 × 103/R1)] × 49 ∴ R1 =198 Ω

Q. The input resistance of a common emitter transistor amplifier, if the output resistance is 500 k $Ω$ , the current gain $α$ = 0.98 and power gain is 6.0625 $\times 1 0^{6}$ , is

198 $Ω$

300 $Ω$

100 $Ω$

400 $Ω$

Voltage gain= $A_{V} = β \frac{R _{2}}{R _{1}}$
Also,current gain $β = \frac{α}{1 - α} = \frac{0.98}{1 - 0.98} = 49$
$A_{V} = (49) [\frac{500 \times 1 0 ^{3}}{R _{1}}]$
Power gain
$= 6.0625 \times 1 0^{6} = 49 \times [\frac{500 \times 1 0 ^{3}}{R _{1}}] \times 49$
$∴ R_{1} = 198Ω$

Q. The input resistance of a common emitter transistor amplifier, if the output resistance is 500 kΩ, the current gain α = 0.98 and power gain is 6.0625 ×106, is

198 Ω

300Ω

100Ω

400Ω