Elektronika Dasar Bipolar Junction Transistor

Steady current established by a dc supply Effect of a control element on

small-signal ac analysis

\

The Importance Parameters

Two-port system

Input impedance:

Voltage Gain

Phase relationship

For the typical transistor amplifier, the input and output signals are either 180° out

of phase or in phase

.

THE r

e

TRANSISTOR MODEL

BJT transistor amplifiers are referred to as current-controlled devices.

Common Base Configuration

Typical values of the Zo are in the mega ohm range

Defining Zo.

If the applied signal is set to zero, then Ic is 0 A,resulting

(Vo and Vi are 18 out of phase)

00

Two-port system

The term “term” or h-parameter was chosen because the mixture of variables( V and I)

Complete hybrid equivalent circuit

Short-circuit input–impedance parameter:

Open-circuit reverse transfer voltage ratio parameter:

Short-circuit forward transfer current ratio parameter:

Open-circuit output admittance parameter:

The common emitter configuration: Ii =Ib, Io=Ic,Vi=Vbe,Vo=Vce

Ie= Ib + Ic

Common-emitter configuration

Common base configuration

Since h

r

is normally a relatively small quantity and resistance determined by 1/h

o

is often large

enough, resulting

Hybrid versus r

e

model

The current source of the standard hybrid equivalent circuit is pointing down rather than in

the actual direction as shown in the re model

Complete hybrid equivalent circuit for a transistor

W

k

5

.

1

1 0 0Ib

33

m

A

/

V

Effect of ro

Zo= ro

||

Rc

Io=

1

Rc

1

Rc

+

1

ro

βIb

=

ro

ro

+

Rc

βIb →

Io

Ib

=

R’=R1||R2=

R

1

+

R

2

¿

R

1.

R

2

¿

Ib =

1

βre

1

βre

+

1

R '

Ii →

Ib

Ii

=

R '

R

'

+

βre

Zi=R’||

βre

Io =

βIb →

Io

Ib

=

β

Zo = Rc

Ai =

Io

Ii

=

Io

Ib

Ib

Ii

=

βR'

R

'

+

βre

Av =

ℜ

¿

−Rc

¿

Effect of r

o

Zo = r

o

||Rc

Av =

−

ro

∨

¿

Rc

ℜ

ro

+

Rc

¿

Io

Ib

=

ro. β

¿

Ai =

Io

Ii

=

Io

Ib

Ib

Io

=

ro

+

Rc

¿

R '

R

'

+

βre

ro . β

¿

Or

Ai =

Rc

¿

Unbypassed

Vi = Ib

β

re +Ie RE = Ib

β

re + β

¿ +1)Ib RE = (

β

r

e + β¿ +1) RE)Ib

Zb =

Vi

Ib

=

β

r

e +( β +1)RE =

¿

β

¿

r

e + RE) (for β >>1)

Ib =

RB

+

Zb

¿

1

Zb

+

1

RB

¿

Ii →

Ib

Ii

=

RB

¿

1

Zb

¿

≅

β

RE (for RE >>

r

e)

Io =

βIb →

Io

Ib

=

β

Zi = RB || Zb Ai =

Io

Ii

=

Io

Ib

Ib

Ii

=

β . RB

RB

+

Zb

or

Zb =

β .

r

e

Av =

−

ℜ

Rc

Vo

=

Io Rc

=

(

Ic )Rc

=

α

Ie.Rc =

α

(

Vi

r e

)

Rc → Av

(since

α≅1¿

Ie

≅Ii

(

for R

E

>>

r

e

)

Io =

−

Ic

=−

α

Ie

¿

−

α

Ii

→ Ai

=−

α

≅

−

1

Effect of

r

o

For typical parameter values the effect of r

o

can be ignored

APPROXIMATE HYBRID EQUIVALENT CIRCUIT

common-emitter

common-base

h

ie = β

r

e

h

ie = β

r

e

h

oe =

1/r

o

h

fb = α

h

ib =

Zi =RB

||

hie

Zo=RC

VO = -IoRC = hfe Ib RC = - hfe

(

Vi

hie

)

RC AV = -

h fe Rc

hie

Ib

≅

Ii ( for RB >> hie Io = hfe Ii hfe

Effect of ro

Hoe =

1

ro

Zo =

1

hoe

|| Rc

re =

hie

hfe

Av = -

hfe

(

1

hoe

∨

¿

Rc

)

hie



CE Emitter –Bias Configuration

Unbypassed



Common Base Configuration

Zi = R

E

||h

ib

Zo = R

c

Ie =

hib

Vi

Vo =

h ib

¿

−Io . Rc=−

(

hfb. Ie

)

Rc=¿−hfb

(

Vi

hib

)

Rc → Av=

−hfb. Rc

¿

Zi = R

B

||

β

r

e

Vi =

Zi

+

Zi

Rs

Vs →

Vs

Vi

=

Zi

Zi

+

Rs

Zo = R

c

Av =

Vo

Vi

=

−

RL

∨

¿

Rc

r e

Avs =

Vo

Vs

=

¿

Vi

Vs

Vo

Vi

=

Zi

Zi

+

Rs

Av

Ii = Is

→ Ai

=

Io

Ii

=−

Av

Zi

RL

Voltage Divider Bias

R’E = RE||RL

Vs –

Ib

.Rs

– Ib βre

β

−

¿

+1)Ib R’E

= 0

→ Ib

=

Vs

Rs

+

βre

+

(

β

+

1

)

R ' E

≅

Vs

Rs

+

β

( ℜ+

R

'

E

)

Ie

βI b

=

Rs

β

+ ℜ+

R

'

E

Vs

¿

¿

Vo =

R

'

E

Rs

β

+ ℜ+

R

'

E

v

s

→

Av

s =

R

'

E

Rs

β

+ ℜ+

R

'

E

Zb =

βre

+(

β

+

1

)

R

'

E

≅

β

(

ℜ+

R

'

E

)

Zo = R

E

|| (

Rs

Philips Semiconductors Product specification

NPN general purpose transistors

BC

107;BC 108;BC;109

PINNING

FEATURES

 Low current (max. 100mA)  Low voltage ( max. 45 V)

APPLICATIONS



General purpose switching and amplification

PIN DESCRIPTION

1 emitter

2 base

DESCRIPTIONS

NPN transistor in a TO-18;SOT 18 metal package PNP complement : BC177

Characteristic

T = 25 C, unless other wise specified

symbol parameters conditions min type max unit

IcBc Collector cut-off current IE = 0; VCB

= 20 V

IE = 0; VCB

= 20 V; T = 125

C

-- -- 1515 nA

μA

IeBc Emitter cut-off current Ic = 0; VEB = 5 V - - 50 nA hFE DC current gain

BC 107A; BC108A

BC107B; BC108B; BC109B BC109C; BC109C

Ic =

10

μA

;VcE = 5 V

-40 10 0 90 15 0 27 0

-hFE DC current gain BC 107A; BC108A

BC107B; BC108B;BC109B BC109C; BC109C

Ic = 2

mA

;VcE = 5 V

11 0 20 0 42 0 18 0 29 0 52 0 22 0 45 0 80 0 VCEsat Collector emitter saturation

voltage Ic = 10 mA; I_{Ic = 100 mA; I}B = _{B =}

0,5 mA

5 mA

-- 9020 0 25 0 60 0 mV mV

VBEsat Base emitter saturation

voltage Ic = 10 mA; I

mA;note 1

B =

0,5

Ic = 100 mA; IB =

5 mA;note

1

-- 700 90 0

-- mVmV

VBE Base emitter voltage Ic = 2 mA; VcE = 5 V; note 2 Ic = 10 mA; VcE = 5 V; note 2 55 0 -62 0 -70 0 77 0 mV mV

NOTES