0195136047.pdf

PROBLEMS 417

+

−

VDD

RD

RG RS

Figure P8.2.3

C

B

E

CE

CC

+

−

VCC

+

−

vL

Ground

iS

+

−

vS

RS

R 2

R 1

CB

RC

RE 1

RE 2

RL

v iL

1

Figure P8.3.2CE amplifier having an unbypassed emitter resistanceRE 1.

8.3.3Consider the CE BJT amplifier of Figure 8.3.1(a)
withR 1 = 1600 ,R 2 = 400 ,RC = 70 ,
RE= 20 , andRL= 150 . The transistor has
β= 70 ,VA=50 V, andICQ=80 mA when
VCC=15 V. Compute the amplifier’s voltage and
current gains. TakeVTto be 25.861 mV.
8.3.4Let the bypass capacitorCEbe removed in Prob-
lem 8.3.3. How would the gains be altered?
8.3.5Let half ofREbe unbypassed in Problem 8.3.3.
How would the gains be altered?
*8.3.6The CE BJT amplifier of Figure 8.3.1(a) has the
following parameters:R 1 =28,000,R 2 =
8000 , RC = 1400 , RE= 700 , RL=
2000 , VCC=24 V, andICQ=5 mA when
β=100 andVA=100 V. Calculate the voltage
and current gains of the amplifier.

8.3.7Let 200ofREbe not bypassed in Problem 8.3.6.

How would the gains be altered?

8.3.8Determine voltage and current gains for the CE

BJT amplifier shown in Figure 8.3.1(a) with the

following parameters:R 1 = 30,000, R 2 =

9000 , RC = 750 , RE = 250 , RL =

1000 , VCC=9V;andICQ=5 mA when

β=150 andVA=50 V.

8.3.9Assuming that the bypass capacitorCEis removed

in Problem 8.3.8, find the voltage and current

gains.

*8.3.10Find an expression for the power gainAPfor a

common-collector stage if the power gain of an

amplifier stage is defined as the ratio of the load

powervLiLto the power delivered by the source

v 1 is. (See Figure 8.3.1 for notation.)