Chapter 03
19
16.10.2011 1 Microelectronics Circuit Analysis and Design Donald A. Neamen Chapter 3 The Field Effect Transistor Neamen Microelectronics, 4e Chapter 3-1 McGraw-Hill In this chapter, we will: Study and understand the operation and characteristics of the various types of MOSFETs. Understand and become familiar with the dc analysis and design techniques of MOSFET circuits. Examine three applications of MOSFET circuits. Investigate current source biasing of MOSFET circuits, such as those used in integrated circuits. Analyze the dc biasing of multistage or multitransistor circuits Neamen Microelectronics, 4e Chapter 3-2 McGraw-Hill circuits. Understand the operation and characteristics of the junction field-effect transistor, and analyze the dc response of JFET circuits.
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Transcript of Chapter 03
16.10.2011
1
Microelectronics Circuit Analysis and Design
Donald A. Neamen
Chapter 3
The Field Effect Transistor
Neamen Microelectronics, 4e Chapter 3-1McGraw-Hill
In this chapter, we will:
Study and understand the operation and characteristics of the various types of MOSFETs.
Understand and become familiar with the dc analysis and design techniques of MOSFET circuits.
Examine three applications of MOSFET circuits.
Investigate current source biasing of MOSFET circuits, such as those used in integrated circuits.
Analyze the dc biasing of multistage or multitransistor circuits
Neamen Microelectronics, 4e Chapter 3-2McGraw-Hill
circuits.
Understand the operation and characteristics of the junction field-effect transistor, and analyze the dc response of JFET circuits.
16.10.2011
2
Basic Structure of MOS Capacitor
Neamen Microelectronics, 4e Chapter 3-3McGraw-Hill
MOS Capacitor Under Bias:Electric Field and Charge
P ll l l iParallel plate capacitor
Negative gate bias: Positive gate bias:
Neamen Microelectronics, 4e Chapter 3-4McGraw-Hill
g g
Holes attracted to gate
g
Electrons attracted to gate
16.10.2011
3
Schematic of n-Channel Enhancement Mode MOSFET
Neamen Microelectronics, 4e Chapter 3-5McGraw-Hill
Basic Transistor Operation
Neamen Microelectronics, 4e Chapter 3-6McGraw-Hill
Before electron inversion layer is
formed
After electron inversion layer is
formed
16.10.2011
4
Basic Transistor Operation
Neamen Microelectronics, 4e Chapter 3-7McGraw-Hill
Current Versus Voltage Characteristics: Enhancement-Mode nMOSFET
Neamen Microelectronics, 4e Chapter 3-8McGraw-Hill
16.10.2011
5
Family of iD Versus vDS Curves:Enhancement-Mode nMOSFET
Neamen Microelectronics, 4e Chapter 3-9McGraw-Hill
p-Channel Enhancement-Mode MOSFET
Neamen Microelectronics, 4e Chapter 3-10McGraw-Hill
16.10.2011
6
Symbols for n-Channel Enhancement-Mode MOSFET
Neamen Microelectronics, 4e Chapter 3-11McGraw-Hill
Symbols for p-Channel Enhancement-Mode MOSFET
Neamen Microelectronics, 4e Chapter 3-12McGraw-Hill
16.10.2011
7
n-Channel Depletion-Mode MOSFET
Neamen Microelectronics, 4e Chapter 3-13McGraw-Hill
Family of iD Versus vDS Curves:Depletion-Mode nMOSFET
Neamen Microelectronics, 4e Chapter 3-14McGraw-Hill
Symbols
16.10.2011
8
p-Channel Depletion-Mode MOSFET
Neamen Microelectronics, 4e Chapter 3-15McGraw-Hill
Symbols
Cross-Section of nMOSFET and pMOSFET
Neamen Microelectronics, 4e Chapter 3-16McGraw-Hill
Both transistors are used in the fabrication of CMOS circuitry.
16.10.2011
9
Summary of I-V RelationshipsRegion NMOS PMOS
Nonsaturation vDS<vDS(sat) vSD<vSD(sat)
Saturation vDS>vDS(sat) vSD>vSD(sat)
Transition Pt. vDS(sat) = vGS - VTN vSD(sat) = vSG + VTN
])(2[ 2DSDSTNGSnD vvVvKi ])(2[ 2
SDSDTPSGpD vvVvKi
2][ TPSGpD VvKi 2][ TNGSnD VvKi
Neamen Microelectronics, 4e Chapter 3-17McGraw-Hill
Enhancement Mode
VTN > 0V VTP < 0V
Depletion Mode
VTN < 0V VTP > 0V
Conduction Parameters
NMOSFET noxn
n L
Wk
L
CWK
'
NMOSFET
PMOSFET
h
poxp
p
nn
L
Wk
L
CWK
LL
'
Neamen Microelectronics, 4e Chapter 3-18McGraw-Hill
where:oxoox tC
16.10.2011
10
Channel Length Modulation: Early Voltage
Neamen Microelectronics, 4e Chapter 3-19McGraw-Hill
Body Effect
Neamen Microelectronics, 4e Chapter 3-20McGraw-Hill
16.10.2011
11
Subthreshold Condition
Neamen Microelectronics, 4e Chapter 3-21McGraw-Hill
NMOS Common-Source Circuit
Neamen Microelectronics, 4e Chapter 3-22McGraw-Hill
16.10.2011
12
PMOS Common-Source Circuit
Neamen Microelectronics, 4e Chapter 3-23McGraw-Hill
Load Line and Modes of Operation:NMOS Common-Source Circuit
Neamen Microelectronics, 4e Chapter 3-24McGraw-Hill
16.10.2011
13
Problem-Solving Technique:NMOSFET DC Analysis
1 Assume the transistor is in saturation1. Assume the transistor is in saturation.a. VGS > VTN, ID > 0, & VDS ≥ VDS(sat)
2. Analyze circuit using saturation I-V relations.3. Evaluate resulting bias condition of transistor.
a. If VGS < VTN, transistor is likely in cutoffb. If VDS < VDS(sat), transistor is likely in
Neamen Microelectronics, 4e Chapter 3-25McGraw-Hill
DS DS( ), ynonsaturation region
4. If initial assumption is proven incorrect, make new assumption and repeat Steps 2 and 3.
Enhancement Load Device
Kn = 1mA/V2
Neamen Microelectronics, 4e Chapter 3-26McGraw-Hill
VTN = 1V
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Circuit with Enhancement Load Device and NMOS Driver
ML is always in saturation.
Neamen Microelectronics, 4e Chapter 3-27McGraw-Hill
MD can be biased either in saturation or nonsaturation region.
Voltage Transfer Characteristics: NMOS Inverter with Enhancement Load Device
vI < VTN vI > VTN
Neamen Microelectronics, 4e Chapter 3-28McGraw-Hill
16.10.2011
15
NMOS Inverter with Depletion Load Device
Neamen Microelectronics, 4e Chapter 3-29McGraw-Hill
CMOS Inverter
Neamen Microelectronics, 4e Chapter 3-30McGraw-Hill
16.10.2011
16
2-Input NMOS NOR Logic Gate
V1 (V) V2 (V) VO (V)
0 0 High
Neamen Microelectronics, 4e Chapter 3-31McGraw-Hill
5 0 Low
0 5 Low
5 5 Low
MOS Small-Signal Amplifier
Neamen Microelectronics, 4e Chapter 3-32McGraw-Hill
16.10.2011
17
Current Mirrors
Neamen Microelectronics, 4e Chapter 3-33McGraw-Hill
2-Stage Cascade Amplifier
Source follower
Neamen Microelectronics, 4e Chapter 3-34McGraw-Hill
Common-source
16.10.2011
18
NMOS Cascode Circuit
Neamen Microelectronics, 4e Chapter 3-35McGraw-Hill
Cross Section of n-Channel Junction Field Effect Transistor (JFET)
Neamen Microelectronics, 4e Chapter 3-36McGraw-Hill
16.10.2011
19
Cross Section of n-Channel MESFET
Neamen Microelectronics, 4e Chapter 3-37McGraw-Hill
