© Bob York

Transistor Basics

Control Terminal

I(V)I(V, Vc)

I(V, Ic)

or

V VVc or Ic

FETs

BJTs

© Bob York

JFETs

Vgs

Gate

Source

Drain

Ids(Vgs,Vds)Vds

Id

Vgs

Vds

Ig = 0

Gate

Source

Drain

Saturation region ID

Vgs ≤ Vt (cutoff)

Ohmic or Triode region

Vds

Vgs= Vt + 0.5

Vgs= Vt + 1.0

Vgs= Vt + 1.5

Vgs= 0

G

D

S

Idss

Incr

easi

ng V

gs

N-ch JFET

N-ch JFET

© Bob York

MOSFET

Vgs

Gate

Source

Drain

Ids(Vgs,Vds)Vds

Id

Vgs

Vds

Ig = 0

Gate

Source

Drain

Saturation region ID

Vgs ≤ Vt (cutoff)

Ohmic or Triode region

Vds

Vgs= Vt + 0.5

Vgs= Vt + 1.0

Vgs= Vt + 1.5

Vgs= Vt + 2.0

GD

S Incr

easi

ng V

gs

NMOS

NMOS

© Bob York

Family Tree

Field-Effect Transistors

JFET, MESFET

Depletion-mode (normally on)

n-ch p-ch

MOSFET

Depletion-mode (normally on)

Enhancement-mode (normally off)

n-ch p-ch n-ch p-ch

© Bob York

BJTs

IbIc=αFIE

Ic

vce

Ib

Base

Emitter

Collector

Ic, , mA Forward active region

VCE

70 μA

Incr

easi

ng I

b

NPN BJT

NPN BJT

B

E

C

IE

vbe

vcb

60 μA

50 μA

40 μA

30 μA

20 μA

10 μA

0 μA

Vce,sat

Ib

Ic=βIB

BC

E

2

4

6

8

Ie

© Bob York

JFET Experiments

Ids

Gate

Source

Drain

Vgs

A

Vds

Vg= ? Vout

Id

+12 V

R = ?

Vout

Id

+12 V

R D

RS = ?

Vgs

© Bob York

2N7000

MOSFET Experiments

ID

Gate

Source

Drain

Vgs

A

Vds 3 V

1 μF

Vout

Id

+10 V

R D

RS = ?

Vgs

Vg=5VVd

Id

+10 V

VgsVs

RS = ?

R D

Vd

Id

+10 V

VgsVs

RS

R D

100 kΩ Ig = 0

Vg=5V

Rg = ?

© Bob York

Vout

MOS & CMOS

+10 V

RS

Vin

0 V

5 V

+10 V

Vin

0 V

5 V

Vout

R D

VDD

Vin

R D

R L

VDD

Vin Vout

R LNMOS

PMOS

Vout

Id

+10 V

R g

Vgs

1 kΩ

200 Ω

3 MΩ

© Bob York

CD4007

2

4

1

5

3

P

N

P

14

13

12

11

10

9

8N

N

P

VDD

VSS

7

6

5

4

3

2

1

14

7

13

8

6

11

9

1210

© Bob York

2N3904

0μA

25μA

50μA

75μA

100μA

125μA

150μA

175μA

200μA

Ib

Co

llec

tor

Cu

rren

t, I

c [

Am

ps]

Collector-Emitter Voltage, Vce [Volts]

2N3904

© Bob York

2N3906

0μA

25μA

50μA

75μA

100μA

125μA

150μA

175μA

200μA

Ib

Co

llec

tor

Cu

rren

t, I

c [

Am

ps]

Emitter-Collector Voltage, Vec [Volts]

2N3906

© Bob York

BJT Experiments

+5 V

0 V

5 V

Vout

Ic

Rb = ?

+10 V

+5 V

2N3904

Rc = ?

Vin

+5 V

2N3904

2N3906

Rb

Rb

Rc

Rc

f = 1 Hz

2N3904