Chuong 1. mdt2

7/25/2019 Chuong 1. mdt2

1/16

Chng 1:p ng tn sthp mch khuch i

Chng 1

P TUYN TN STHP CA MCH

KHUCH I GHP RC1.1. p ng tn sca mch khuch i Mi mch khuch i u c mt khong tn shot ng nht nh, gi

l bng thng (Band width) hot ng ca hthng.K hiu: BW = [fH fL] (Hz)

Mch khuch i c c trng bi hm truyn hskhuch i, cgi l Aihay Av. p tuyn bng thng ca mch khuch i

)(dBAx

f(Hz)

A

2

mA

fL fH

Midband

1.2. Phng php kho st p ng tn sca mch khuch i

Cc bc kho st:

i. Bc 1: Vmch tng ng vng tn shot ngii. Bc 2: Thit lp biu thc ca hm truyn hsK

iii. Bc 3: Vbiu Bode cho tn sv pha

V d: Cho mch in tng ng sau

0

Vo

I1ieC

R1

R2Rc

V1vi

+

-

Ta c

jwC

1R

jwC

1R

R

1Rc

v

i

i

Rci

Vi

VoA

2

2

1

i

e

e

e

v

+

+

===

1

7/25/2019 Chuong 1. mdt2

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)R//R(jwC1

)jwCR1(

RR

Rc

jwC

)RR(RR

)jwC

1R(

RcA21

2

2121

21

2

v ++

+=

++

+=

Vy)R//R(jwC1

)jwCR1(

RR

RcA

21

2

21

v ++

+=

t)R//R(C

1w,

CR

1w

21

2

2

1 ==

=>

)w

wj1(

)w

wj1(

RR

RcA

2

1

21

v

+

++=

Vy:2

2

2

1

21

v

)w

w(1

)w

w(1

RR

RcA

+

++= (1)

v )w

w(arctg)

w

w(arctg

21

= (2)

V u Bode cho tn stn hiu

Khai trin decibel ta c:

bi

( ) 22

2

121

vvlg20A + )

w

w(1lg20)

w

w(1)

RR

Rclg(20Alg20dB +++

== (dB)

Hay210v

AAA)dB(A ++=

Xp xgn ng

>>

=

=

+=

)ww(wwlg20

)Ww(dB3

)0w(dB0

)w

w(1lg20A

1

1

1

2

1

1

Biu Bode cho A1

2

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Biu Bode cho cc A0, A1, A2

)(dBA1

w(rad/s)

Biu Bode tng ca Av

Biu Bode cho pha tn hiu

Ta c )w

w(arctg)

w

w(arctg =

21

t21 +=

Xp xgn ng

>

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Biu Bode cho gc pha tng

1.3. Kh BJT ghp RC

2 loi

ass cc E transistor (Emitter bypass capacitor). Kho

Lu

o st p ng tn sthp ca mch khuch i

Phng php kho st: n gin cho vic kho st ta tch raghp RC ring bit

Ghp tbypst p tuyn tn strn mch ny nhcc bc nu trn

Ghp tng vo v ra (Coupling capacitor)

:

Do c im chc nng ca mi loi tghp trong m n quyt nh

n cc gi trC coupling sao cho

V d: kho st p tuyn tn sthp c a mch khuch i sau

snh hng n hot ng ca mch khuch i. TEmitter quytnh tn sct di ca mch. Tcoupling chng vai tr l tlien

lc gia ng vo v ra.Khi thit kmch ta ch

)coupling(L)terBypassemit(Lff >>

45o

101w 1w 110w

10

2w2w 210w

w(Rad/s)

- 45o

- 90o

90o

101w 110w

102w

210ww(rad/s)

o

4

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Vcc

0

Re

RcCc

R2 Ce

R1

Cb

ri RLi

1K

602k

2k

10k 100

Beta = 100hi e = 1K

a.

p ng ca tBypassBqua nh hng ca cc tCoupling bng cch ni tt chng, xt mchtng ng tn hiu nhnhsau:

iibi

bi

i

i

Rc1k

Re60

hie

Rb1k

ri10k

RL100Ce

iibi b

i

i

ri10k

hie

Rb1k

Rc1k

Re60

CeR10

bi

ib

iL

iBi iRr )//(Rc1k

Re60

ri//Rb hie

RL100Ce

5

7/25/2019 Chuong 1. mdt2

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Rc

1k

RL

100Re60 Ce

iL

ie

iBi iRr )//(

)//( ieBi hRr +

Ta c,i

bii

bii

e

e

L

i

L

ii

)R//r(i

)R//r(i

i

i

i

i

iA ==

)R//r(

Cj

1

R

Cj

1R

)hr//R(

1

RR

Rbi

ee

e

e

ieiB

LC

C

+

+

+

+=

e

e

e

i

ei

e

e

LC

biC

Cj

R

Cj

RRR

Cj

1R

RR

)R//r(R

++

+

+

= , vi

=+

= 20)hr//R(

R ieiBi

[ ])R//R(jC1)RR(RCj1

RR

)R//r(R

eieei

ee

LC

biC

++

+

+=

Hay,[ ])R//R(jC1

RCj1

)RR)(RR(

)R//r(RA

eie

ee

eiLC

biC

i ++

++

=

2

1

j1

j1

)6020)(100K1(

)K1//K10(K1

+

+++

= , Vi

==

==

s/Rad23.133C)R//R(

1

s/Rad3.33CR

1

eie

2

ee

1

6

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Vy,

2

1i

j1

j1

33.10A

+

+= , hoc

2

1i

f

fj1

f

fj1

33.10A

+

+= , vi

=

=

Hzf

Hzf

25.21

3.5

2

1

2

2

2

1

dBi1log201log2020A

++

++= (dB)

li trung tn (hskhuch i trung tn):c nh ngha lgi trca hskhuch i ti tn sct di ca mch, hay

.)f(AALiim

=

Biu Bode

20

)(dBAi

33.3

20dB/decade

133.23

Mid-bank gain

32dB

L

w(rad/s)

)(dBAi

w(Rad/s)

w1 10w1

20

20dB/decade

w2 10w2

A1

A2

A0

Theo tnh cht ca biu Bode tn sct di ca mch

, hays/Rad23.133L= Hz25.21f

L=

Biu pha

45o

101w 1w 110w

10

2w

2

w2

10ww(Rad/s)

90o

- 45o

- 90o

Biu pha tng hp

7

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ng ca tcouplingb.pypass bng cch ni tt n, ta xt mch tngBqua nh hng ca tB

ng tn hiu nhnhhnh di.

Dng php bin i tng ng Thevenin ta c

(error: ngun p, thiu k hiu i0)

Ta c,i

ii

ii

0bbLLi

iiiiiA

0bbi i

ir

iriiii

==

i

ieb

b

iieB

B

C

LC

C r

h//RCj

1r

1

hR

R

Cj

1RR

R

+++

++

=

[ ] [ ])h//Rr(Cj1)RR(Cj1CjCj

hR

rRR

iebibCLC

bC

ieb

ibC

++++

+=

45o

10

1w 1w

110w

10

2w

2w 210w w(rad/s)

90

- 45o

- 90o

1

2

o

027

Rc1k

R1

Rb1k

ri10k

hie

Cb Ceib

bi

iL

ii

Cb Ceri

Rc1k

hie RL

100Rb

1k

10k

ib

bi

iL

iiir

8

7/25/2019 Chuong 1. mdt2

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n gin ta chcn xt cc tn sct di:

)RR(CCLC

1L +1

= , v)h//Rr(C

iebib

2L +1

=

Do mc ch thit k l cc tCoupling chng vai tr tlin lcgia ng vo v ra. N mch hot ng n nh, tc cc tn sct do

ca tan

tcoupling skhng nh hng n tn sct di ca mch (fLng vitBypass), th:

2L1L,

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0

1MEGVi RdRs

r i

RgCs

gsmvg

G S

rds

D iLi0

Mch tng ng thevenin

0

1MEGVi Cs

Rs Rd

r i

Rg

D iLi0G S rds

gsdsm vrg

+ _

Ta c, , v dtsggs

vvv =dsm

rg=

0

RdRLCs

Rs

S rds D iLi0

iv

+ _+_

Sv

Dng php bin i tng ng Thevenin cho on mch MO

0

Cs

Rs

RL

Rd

Srds iv

+ _+_Sv

Di0 iLM

10

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0

Rd

RLsR)1( +

)1( +sC

iv+ _ Di0 iLrdsM

Vy,i

i

i

0

0

LL

i

L

vv

v

v

i

i

iR

v

vA

==

( )

+++

+=

)]Cj

1//(R[1R//Rr

1

RR

RR

S

SLddsLd

dL

SS

SdLds

dL

SS

S

dLds

dL

CRj1

R

)1(

R//Rr

1)R//R(

)1(

CRj1

R)1(R//Rr

1)R//R(

++

+++

=

++

++=

t)1(

R//RrR dLds

i ++=

Ta c,

SSiSi

SS

dL

SS

S

i

dLvRCRRjR

CRj1)R//R(

)1(

CRj1

RR

1)R//R(

)1(A

+++

+=

+++

=

S

Si

iS

SS

Si

dL

SiSSi

SS

dL

CRR

RRj1

CRj1

RR

R//R

)1(CRRjRR

CRj1)R//R(

)1(

++

+++

=+++

+=

Hay,SSi

SS

Si

dLvC)R//R(j1

CRj1

RR

R//R

)1(A ++

++=

Vit gn li ta c:

11

7/25/2019 Chuong 1. mdt2

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( )

=

=

=

SSi

2

SS

1

dLdsmvm

C)R//R(1

CR

1

R//R//rgA

2

1

vmv s

sAA

+

+= , trong

b.p ng ca tghp cc mng

Mch tng ng tn hiu nhnhhnh v

L

d +

RV-

i

-

Vi

g

r

Lgs V

Vds

r

ggs R

m

+ Cd

R

Hm truyn ca mch:

i

gs

gs

L

i

L

vv

v

v

v

v

vA ==

ig

g

d

Ldds

d

L

Lm

vrR

R

sC

1R//R//r

sC

1R

RgA

+

+

+=

V rt ln do gR 1rR

R

ig

g +

L

vmvs

sAA+

= . Trong :

( )

( )

+

=

=

ddsLd

L

dLdsmvm

R//rRC

1

R//R//rgA

c.

p ng ca tghp cc cng

Mch tng ng tn hiu nhnhhnh v

12

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L

i

d

+

R

V

Cd

- -

Vi

g

rL

gs

VV

ds

r

ggs R

m

+

R

Hm truyn ca mch:

( )

dig

g

Lddsmv

i

gs

gs

L

i

L

v

sC

1

rR

RR//R//rgA

v

v

v

v

v

vA

++

=

==

L

vmvs

sAA+

= . Trong :

( )

( )

+=

=

gid

L

dLdsmvm

RrC

1

R//R//rgA

Gi tr thng rt ln nngR L rt nhv vy Cd nh hng rt t n mo tn s

thp, mo chnh hng do Cs gy ra.

13

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Bi tp chng 1

1.1Cho mch nhhnh:

I iRe

Rb RL

100

Ce

5uF4K 1K

IL

Cho bit .50h;K1h feie ==

a. Vmch tng tn hiu nhtn sthp

b. Tm hm truyn )s(i)s(i

Ai

Li =

c. Vbiu Bode cho bin v pha

1.2Vbiu Bode cho bin v pha ca hm truyn:

( )( )( )( )( )( )

++++++

=2000s12s2s

400s300s10s10A 4

1.3Cho mch nhhnh:

VCC

I i

I L

10uF4K

10K 10K1K

Cho bit .100h;K1h feie ==

a. Tm hm truyn)s(i

)s(iA

i

L

i=

b. Vbiu Bode cho bin v pha

1.4 Cho mch nhhnh:

14

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15/16


1K

+

Vi

-

Vcc=10V

Ve

1K

Cc

1K

5K

5K

Bit .100hfe=

a. Tnh ton phn cc cho mchCE,CQ

VI

b. Vmch tng tn hiu nhtn sthp

c. Tm hm truyn)s(i

)s(iA

i

L

i=

d. Xc nh Cc tn sct thp 3dB l 5Hz.

1.5Cho mch nhhnh:

R1

10K Ce

Cb

RL

47K

180

Vcc (12V)

iri

0

Rc

Re 1K

Cc

100uF

1K

Bit gm= 5.10-3

, Cgs= 20pF, Cgd= 0.5pF, rds=17Ka. Vmch tng ng tn hiu nhtn sthp ca mch in trn

b. Tnhi

L

ii

iA =

c. Vbiu Bode v pha cho p ng min tn sthp ca mch

15

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1.6Cho mch nhhnh:

-

Vdd

Q2FET N

5K

Vi100K 250

5K

250100K

LV

+

100uF

Bit -13

mds10.5g;K5r ==

a. Tmi

L

vV

VA =

b. Tmi

L

vV

VA = nu tBypass cc ngun ni song song chai in tr250

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Chuong 1. mdt2