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

(a). `beta=(DeltaI_(c))/(DeltaI_(B))=(2mA)/(20muA)=100`
(b) The inpute resistance `R_(BE)=(DeltaV_(BE))/(Deltal_(B))=(20mV)/(20muA)=1kOmega`
(c). Transconductance`=(Deltal_(C))/(DeltaV_(BE))=(2mA)/(20mV)=0.1` ohm.
(d). The change in output voltage is `DeltaR_(L) Delta I_(C)=(k'W)(2mA)=10V`.
The applied sigma voltage`=20mV`
Thus, the voltage gain is `(10V)/(20mV)=500`.