Penguat CC (Common Collector)

+VCC

VOUT

VIN VCE

+10V

+1,3V

+2V

1KRE

+10V

+2,3V

+3V

1K

Disebut juga :• Penguat Kolektor Bersama • Pengikut Emiter (Emitter Follower)

IC

VCE

IC

VCE

10mA

10V

VCC = IE.RE + VCE

IC ≈ IE = (VCC – VCE) / RE

vout = ie.RE

vin = ie (RE + re’)

A = vout / vin = RE / (RE + re’)

Jika RE >> re’ maka

A ≈ 1

Contoh 8-1

10K

4K310K

+10V

+1V

-1V

0

+6V

+4V

+5V

+5,29V

+3,31V

+4,3V

VTH = 10V.(10K / 20K) = 5VVE = 5V – 0,7V = 4,3VVC = 10VIE = VE / RE

= 4,3V / 4,3K = 1 mAre’ = 25mV/1mA = 25A = 4300 / (4300 + 25) = 0,994vout = 0,994 x 1V = 0,994V

Model AC dari penguat CC

R1

RER2

+VCC

vout

vs

RS

R1 // R2 vin

RS

vs

RS // R1 // R2

vs

re’

RE

ic

vout

R1 // R2 vout

vin

re’ + (RS//R1//R2)/b

zin(basis) = b(RE + re’) ≈ b.RE

zin = R1 // R2 // zin(basis)

≈ R1 // R2

zout(emiter) = r e’ + (RS // R1 // R2)/b

zout = zout(emiter) // RE

Jika RE sangat besar maka :

zout ≈ zout(emiter)

A = RE / {RE + re’ + (RS // R1 //R2)/b}

R1

RER2

+VCC

vout

vs

RS

zin(base)zin zout(emiter) zout

zout

zin

vin vout

A.vin

zout(emitter)

R1//R2

vin vout

vin

Model AC Model AC yang disederhanakan

Jika b.zin(base) sangat besar maka zin ≈ R1//R2

Jika RE>>zout(emitter) maka zout ≈ zout(emitter)

Contoh 8-3

10K

4K310K

+10V

vout

100mV

3K6

zin = R1//R2

= 5kre’ = 25 (dari soal lalu)RS//R1//R2 = 2,09kb = 100zout(emitter) = 25 + 2,09k/100 = 45,9zout ≈ 45,9

vin = 100mV.(5k/8k6) = 58,1mVJika A = 1 makavout = 58,1mV

Penguat Darlington

Q1R1

RER2

+VCC

voutvs

RSQ2

IE2

IE1

IE2 = (VTH – 2.VBE)/RE

IE1 = IB2 ≈ IE2/bDC

zin2 = b2.RE

zin1 = b1.b2.RE

Karena ini sangat besar maka :zin ≈ R1//R2

rth = RS//R1//R2

zout1= re1’ + rth/b1

zout2= re2’ + zout1/b2

= re2’ + (re1’ + rth/b1)/b2

Regulator Seri

VOUT = VZ – VBE

IB = IL/bDC

Zout = re’ + RZ/b

Disipasi Daya :PD = VCE.IC

VCE = VIN – VOUT

Jika b sangat besar makaIC ≈ IE

VZ

RS

RL

VIN VOUT

IB

IZ

IS

IL

Contoh 8-6

10V

680

15

20V VOUT

IB

IZ

IS

IL

Hitung IZ jika b = 80IS = (20V – 10V) / 680 = 14,7mAVOUT = VB – VBE =10V – 0,7V = 9,3VIE = VOUT / RL

= 0,62AIB = IE/b = 0,62A / 80 = 7,75 mAIZ = IS – IB = 14,7mA – 7,75mA = 6,95mA

PD = (20V – 9,3V).0,62A = 6,63Wre’ = 25mV/0,62A = 0,04zout = 0,04 + 7/100 = 0,11