Question

A load resistor of `2 k Omega `is connected in the collector branch of an amplifier circuit using a transistor in common-emitter mode.The current gain`beta-50`.The input resistance of the transistor is `0.50 k Omega`. If the input current is changed by `50 mu A `,(a)by what amount soes the output voltage change by ,(b)by what amount does the input voltage change and (c) what is the power gain ?

Answer 1

Given:`R_(L)=2kOmega=2xx10^(3)Omega,beta=50`
`r_(i)=0.50kOmega=0.5xx10^(3)Omega`
`DeltaI(B)=50muA=50xx10^(-6)A`
(a) `v_(0)=DeltaI_(C )R_(L)=betaDeltaI_(B)R_(L)=50xx50xx10^(-6)xx2xx10^(3)=5V`
(b) `DeltaV_(BE)=DeltaI_(B)r_(i)=50xx10^(-6)xx0.5xx10^(3)=25xx10^(-3)V`
(c ) `A_(p)=beta^(2)(R_(L))/(r_(i))=(50)^(2)((2xx10^(3))/(0.5xx10^(3)))=10000`