60 For the circuit as shown in the following figure use the

(60%) For the circuit as shown in the following figure, use the given output characteristics of the power transistor and assume that I_BQ is 10mA and the input ac signal results in a I_b(ac) of 2mA (peak value) to Calculate I_CQ and the DC input power provided by the DC supply Calculate I_C(ac)-peak, the ac output power delivered to the primary side of the transformer and power efficiency eta. Calculate the ac output power delevered to the load. Compute the maximal output power P_0(ac)max that can be delivered by the configuration and also the maximal power efficiency eta_max.

Solution

a) in the output characteristics is clearly that ICQ is aprox. 250mA.

b) for a bjt transistor we know that: Ic=B*Ib, or Ic=hfe*Ib, assuming hfe=150

ICac=150*2mA=300mA

c) IL=2*ICac=600mA,

the maximum Power occur when Ib=14mA --> Ic=2.1A, IL=4.2A

PLmax=(4.2)^2*5ohm=88.2W