Penguat Emiter Sekutu

RC

RE

R1

R2

+VCC

RS

0V

VB

RL

0V

Rangkaian Ekivalen

RS

RL

RC

RE

R1

R2

+VCC

RC

RE

R1

R2

+VCC

Rangkaian Ekivalen DC

RCR1 R2

RS

RL

Rangkaian Ekivalen AC

Resistansi Emiter AC

re’ = Vbe / Ie atau

re’ = vbe / ie

Harga pendekatan : re’ = 25mV / Ie

Beta AC = Ic / Ib

= ic / ib

Penguatan Teganganie = vin / re’

ic ≈ ie

vout ≈ -ic.Rc

≈ - vin .RC / re’

A = vout / vin ≈ - RC / re’

Impedansi Masukan

RCR1 R2

RS

re’vini1 i2

ib

zin zin(basis)

RCR1 R2 b.re’vini1 i2

ib

zin zin(basis)

ic

zin = zin(basis) // R1 // R2zin(basis) = b.re’

Impedansi Keluaran

RCR1 R2 b.re’vini1 i2

ib

zin zin(basis)

ic

zout

ic

zout ≈ RC

Contoh 7-1

3K6

1K

10K

2K2

+10V

vin

VB = 10V.2K2 / (10K + 2K2) =1,8VVE = VB – VBE = 1,8V – 0,7V = 1,1VIE = VE / RE

= 1,1V / 1K =1,1mAVC = VCC – IC.RC

= 10V – 1,1mA.3K6 = 6,04V

re’ = 25mV / 1,1mA = 22,7WA = RC / re’

= -159