Chapter 12 : Field – Effect Transistors

12-1 NMOS and PMOS transistors12-2 Load-line analysis of a simple NMOS

amplifier12-3 Small –signal equivalent circuits12-4 Common source amplifiers12-5 Source followers12-6 CMOS logic gates

MOSFET Transsistors

N-channel enhancement MOSFET

4-1. Device Structure . Fig. 4-1 . Physical structure of the enhancement- type NMOS transistor

Fig. 4-2 . The enhancement-type NMOS transistor with applied voltage

Applying a small vDS . Fig. 4-3 An NMOS transistor with vGS > vt and

s small vDS

Operation in the cut - off

Fig. 4-4 . The iD –vDS characteristics of the MOSFET

With increasing vDS . Fig. 4-5 The enhancement NMOS transistor as vDS is increased

Fig. 4-6 The drain current iD vs vDS

Fig. 4-11 The iD – vDS characteristics of an n-channel enhancement type MOSFET

Fig. 4-12 The iD-vDS characteristic for an enhancement –type NMOS transistor in saturation

Fig. 4-7 A tapered shape caused by increasing vDS

Fig. 4-10 Circuit symbol for the n-channel enhancement –type MOSFET

The p-Channel MOSFET

• vGS , vDS and vt are negative

• iD enters from the source terminal and leaves through the drain terminal .

• NMOS operates faster and at lower power than PMOS .

Fig. 4-13 Large signal equivalent circuit of an n-channel MOSFET

Fig. 4-17 Large signal equivalent circuit of the n-channel MOSFET in saturation with r0

Fig. 4-37 Small signal models for the MOSFET

Fig. 4-37 (b) with the channel length modulation

Fig. 4-40 T model of the MOSFET with r0

Chapter 12 : Field – Effect Transistors

12-1 NMOS and PMOS transistors12-2 Load-line analysis of a simple NMOS

amplifier12-3 Small –signal equivalent circuits12-4 Common source amplifiers12-5 Source followers12-6 CMOS logic gates

Common- source amplifiers

Common- source amplifiers

10.3 CMOS Logic Gate Circuits10.3.1 Basic structure

Fig. 10.8 Representation of a three- input CMOS logic gate