2016-02-04Mobile Communication Lab. ( pknu.ac.kr)1 Chapter 8. Transistor bias.

23年 5月 3日 Mobile Communication Lab. (http://mobile pknu.ac.kr)

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Chapter 8. Transistor bias


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8-1. VDB (Voltage-Divider Bias)

CCBB VRR

RV

21

2

BEBBE VVV

E

EE R

VI

EC II

CCCCC RIVV

ECCE VVV

(βdc 에 무관 )


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8-2. Accurate VDB Analysis

VTH

RTH 21

2121 RR

RRllRRRTH

CCTH V

RRR

V

21

2

EC

CECC

RRVV

LL

.부하선EC

CCsatC RR

VI

)(

THEEBETHB VRIVRI

BETHdc

THEE VV

RRI )(

dc

THE

BETHE R

R

VVI

보통 R2<R1 이므로 RTH R2

dc

THE

RR

100 dcETH RR )01.0(

dcERR )01.0(2


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8-3. VDB Load Line and Q point

①

②

mAkVI E 111.1

mAkVI E 5.02.21.1

③ mAVI E 15.25101.1

(for RE = 1k)(for RE = 2.2k)(for RE = 510Ω)

* Q Variation points: VCC, R1, R2, RC

* But RE → Simple Variations of Q point


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8-4. Two-supply Emitter Bias

VBE+

-

①E

BEEEE R

VVI

)0( EEEEBE VRIV

② 0 EEEEBEBB VRIVRI

)(dc

BE

BEEEE R

R

VVI

dc

BE

RR

100 EdcB RR 01.0


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ex ) VVVBE 3.1)2(7.0

mAkVI E 3.113.1

VkmAVVC 32.5)6.3)(3.1(10

VVVVVV ECCE 02.6)7.0(32.5

* Simplify

0BV

E

EEE R

VVI

7.0

CCCCC RIVV

VVV CCE 7.0


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8-5. Other Types Biasing

① Base Bias

Switching


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② Emitter-feedback Bias

βdc ( 大 ) → IC ( 大 ) → VRE ( 大 )

(a)(b) βdc 영향

CCCCEECE VRIRIV EC

CECCC RR

VVI

)( CE II

CCEEBBBE VRIRIV

→ VRB ( 小 ) → IB ( 小 )→ IC ( 小 ) → βdc ( 감소 )

( 고찰 )

,( CE II )dc

CB

II

)(dc

BE

BECCC R

R

VVI

if )dc

BE

RR

→ βdc 영향 무시가능

* βdc 의 3 : 1 변화는 IC 를 거의 3 : 1 로 변화시킴

RB RC

RE

VCC


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ex 8.6 )

EEVRR

RV

21

22 ( VRL )

21 RR

VI EE

VVVE 7.02 ( VRE )

E

EE R

VI

CEC RIV

210 VVVB

EE VVV 10


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mAkVI 82.02.12

10

VkmAV 8.12.2)82.0(2 ( VR2 )

VVE 1.17.08.1 ( VRE )

mAkVI E 1.111.1

VkmAVC 96.3)6.3()1.1(

(Base - GND) VVVVB 2.88.110

(Emitter - GND) EE VVVV 101.110


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③ Collector-feedback Bias (or self-bias)

IB + IC

IC

* βdc 3 : 1 → IC 2 : 1less

βdc ( 大 ) → IC ( 大 ) → VRC ( 大 ) → VRB ( 小 ) → IB ( 小 ) → IC 감소

* CCCCBCE VRIIV )(

C

CECCC R

VVI

포화전류 :

차단전압 :C

CC

RV

CCV

IB


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* βdc 영향

CCCCBBBBE VRIIRIV )(0

dc

BC

BECCC R

R

VVI

→ 포화점에 달할 수 없다

dcCB RR 로 하면 )2

(C

BECCC R

VVI

부하선의 중앙점

+

--+ 0.7

>0.7( 포화점에 달할 수 없다 )


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④ Collector-AND Emitter-feedback Bias

dc

BEC

BECCE R

RR

VVI

EEE RIV

VVV EB 7.0

CCCCC RIVV


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8-7. PNP Tr

+-

VCE

+

+

-

-VBE

VCB ① npn Tr → pnp Tr 로 교체

② 전류 , 전압을 모두 역으로

-VCC+VE

E+

-V2

VBI VE’

VC

IE +

-VE (VRE)

동일

2016-02-04Mobile Communication Lab. ( pknu.ac.kr)1 Chapter 8. Transistor bias.

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Transcript of 2016-02-04Mobile Communication Lab. ( pknu.ac.kr)1 Chapter 8. Transistor bias.