0195136047.pdf

PROBLEMS 421

B

C

E

−12 V

1 kΩ

25 mV
rms

4.5 kΩ

55 kΩ 6 kΩ

25 μF 25 μF, 12 V

100 μF 50 μF

(c)

2.4 kΩ 0.24 kΩ

0.6 kΩ 0.1 kΩ

BJT

2N104

BJT

b 2N104

1.2 kΩ

a

First stage Second stage

RB hie hfeIB

IB

IL

RL

I 2

IS R 2

B C

E

(d)

Useful output current of first stage

(Input current of second stage)

Net input resistance

appearing at base terminal

of second transistor

RB hie hfeIB

IB C CC

Coupling

capacitor

IL

RL

I 2

IS R 2

B

E

(e)

VC

RB

CT IL

RL

I 2

IS R 2

BC

E

(f)

RBB′

Base

spreading

resistor

RB′E

Forward

biased

resistor

CD

Diffusion

capacitor

IB ID

B′ II IT IC

gmVB′E = hfeIB

Transition

capacitor

Figure P8.5.6Continued