Question

The output resistance of a common emitter transistor amplifier, if the input resistance is $200Î\copyright$ ( $Î\pm =0.98$ and power gain is $5×{10}^6,$ is)

• A. $516kÎ\copyright$
• B. $216kÎ\copyright$
• C. $300kÎ\copyright$
• D. $416kÎ\copyright$

Answer 1

Answer: (D)

We know that Voltage gain,
$ΔV=β\frac{R_o}{R_i}$
Also, $β=\frac{Î\pm }{1−Î\pm }=\frac{0.98}{1−0.98}=49$
$ΔV=(49)\left(\frac{R_0}{200}\right)$
Power gain AP
$ΔP$ = Current gain $(β)×$ voltage gain $(ΔV)$
$⇒$ $5×{10}^6=49×49×\frac{R_o}{200}$
$⇒$ $R_e=\frac{5×{10}^6×200}{49×49}=0.416×{10}^6≃416kÎ\copyright$