A transistor is used in common-emitter mode in an amplifier circuit. When a signal 20mV is added to the base-emmiter voltage,the base current changes by `20(mu)A `and the collector current changes by 2mA.The load resistance is `5k(Omega)`.Calculate (a)the factor`(beta)`(b)the input resistance `R_(BE),`(c) the transconductance and (d) the voltage gain .

Explanation

Given `v_(i)=DeltaV_(BE)=20mV=20xx10^(-3)V`
`DeltaI_(B)=20mu=20xx10^(-6)A`
`DeltaI_(C)=2mA=2xx10^(-3)A,R_(L)=5kOmega=5xx10^(3)Omega`
(a). `beta=(DeltaI_(C))/(DeltaI_(B))=(2xx10^(-3))/(20xx10^(-6))=100`
(b). `r_(i)=(DeltaV_(BE))/(DeltaI_(B))=(20xx10^(-3))/(20xx10^(-6))=1000Omega`
(c). `g_(m)=(DeltaI_(C))/(DeltaV_(BE))=(2xx10^(-3))/(20xx10^(-3))=0.1 mho
(d). `A_(v)=beta(R_(L))/(r_(i))=100xx(5xx10^(3))/(10^(3))=500`