Chapter 12 : Field – Effect Transistors 12-1 NMOS and PMOS transistors 12-2 Load-line analysis of a simple NMOS amplifier 12-3 Small –signal equivalent circuits 12-4 Common source amplifiers 12-5 Source followers 12-6 CMOS logic gates

MOSFET Transsistors

N-channel enhancement MOSFET

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

Fig The enhancement-type NMOS transistor with applied voltage

Applying a small v DS. Fig. 4-3 An NMOS transistor with v GS > v t and s small v DS

Operation in the cut - off

Fig The i D –v DS characteristics of the MOSFET

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

Fig. 4-6 The drain current i D vs v DS

Fig The i D – v DS characteristics of an n- channel enhancement type MOSFET

Fig The i D -v DS characteristic for an enhancement –type NMOS transistor in saturation

Fig. 4-7 A tapered shape caused by increasing v DS

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

The p-Channel MOSFET v GS, v DS and v t are negative i D enters from the source terminal and leaves through the drain terminal. NMOS operates faster and at lower power than PMOS.

Fig Large signal equivalent circuit of an n- channel MOSFET

Fig Large signal equivalent circuit of the n- channel MOSFET in saturation with r 0

Fig Small signal models for the MOSFET

Fig (b) with the channel length modulation

Fig T model of the MOSFET with r 0

Chapter 12 : Field – Effect Transistors 12-1 NMOS and PMOS transistors 12-2 Load-line analysis of a simple NMOS amplifier 12-3 Small –signal equivalent circuits 12-4 Common source amplifiers 12-5 Source followers 12-6 CMOS logic gates

Common- source amplifiers

10.3 CMOS Logic Gate Circuits Basic structure Fig Representation of a three- input CMOS logic gate