E&CE 319 Basic Circuits

Review:: BJT small-signal equivalent circuit models

(1) Hybrid- model

and ,

Where VT = 25mV is the thermal voltage

Ic: is the DC current at collector (2) T-model

and ,

Where VT = 25mV is the thermal voltage

Ic: is the DC current at collector

IE: is the DC current at emitter

vbe

E

vbe

_

ib

+

ie

_

+

ie

ib

ic

ic

ib

gmvbe

E

vbe

E

ib

Voltage-controlled current source

vbe

_

+

ie

ic

gmvbe

re

C

B

Current-controlled current source

ib

_

C

+

E

ie

re

ic

B

C

C

Current-controlled current source

E

B

ib

Voltage-controlled current source

C

r

B

r

B

_1168618257.unknown

_1168618714.unknown

_1168618206.unknown