Microelectronics Basic Structure of MOS Capacitor MOS Capacitor

Transcription

9/2/2013
In this chapter, we will:
Microelectronics
Circuit Analysis and Design
Study and understand the operation and characteristics of
the various types of MOSFETs.
Donald A. Neamen
Understand and become familiar with the dc analysis and
design techniques of MOSFET circuits.
Examine three applications of MOSFET circuits.
Chapter 3
Investigate current source biasing of MOSFET circuits, such
as those used in integrated circuits.
The Field Effect Transistor
Analyze the dc biasing of multistage or multitransistor
circuits.
Neamen
Microelectronics, 4e
McGraw-Hill
Chapter 3-1
Neamen
McGraw-Hill
Chapter 3-2
MOS Capacitor Under Bias:
Electric Field and Charge
Basic Structure of MOS Capacitor
Parallel plate capacitor
Negative gate bias:
Neamen
McGraw-Hill
Chapter 3-3
Neamen
McGraw-Hill
Holes attracted to gate
Chapter 3-4
1
9/2/2013
Basic Transistor Operation
Schematic of n-Channel
Enhancement Mode MOSFET
Before electron
inversion layer is
formed
Neamen
McGraw-Hill
Chapter 3-5
Current Versus Voltage Characteristics:
Enhancement-Mode nMOSFET
Neamen
McGraw-Hill
Chapter 3-7
Neamen
McGraw-Hill
After electron
inversion layer is
formed
Chapter 3-6
Family of iD Versus vDS Curves:
Enhancement-Mode nMOSFET
Neamen
McGraw-Hill
Chapter 3-8
2
9/2/2013
p-Channel Enhancement-Mode
MOSFET
Neamen
McGraw-Hill
Chapter 3-9
Symbols for p-Channel
Enhancement-Mode MOSFET
Neamen
McGraw-Hill
Chapter 3-11
Symbols for n-Channel
Enhancement-Mode MOSFET
Neamen
McGraw-Hill
Chapter 3-10
n-Channel Depletion-Mode MOSFET
Neamen
McGraw-Hill
Chapter 3-12
3
9/2/2013
Family of iD Versus vDS Curves:
Depletion-Mode nMOSFET
p-Channel DepletionMode MOSFET
Symbols
Neamen
McGraw-Hill
Symbols
Neamen
Chapter 3-13
Summary of I-V Relationships
Region
NMOS
Nonsaturation
vDS<vDS(sat)
Conduction Parameters
vSD<vSD(sat)
2
SD
iD = Kn[2(vGS −VTN)vDS −v ] iD = Kp[2(vSG +VTP)vSD −v ]
vDS>vDS(sat)
i D = K n [vGS − VTN ]2
NMOSFET
Kn =
PMOSFET
Kp =
vSD>vSD(sat)
iD = K p [vSG + VTP ]2
Transition Pt.
vDS(sat) = vGS - VTN
vSD(sat) = vSG + VTP
Enhancement
Mode
VTN > 0V
VTP < 0V
Depletion
Mode
VTN < 0V
VTP > 0V
where:
Neamen
Chapter 3-14
PMOS
2
DS
Saturation
McGraw-Hill
McGraw-Hill
Chapter 3-15
Neamen
Wµ n Cox
W
= k n'
2L
2L
Wµ p Cox
2L
= k p'
W
2L
Cox = ε o tox
McGraw-Hill
Chapter 3-16
4
9/2/2013
Problem-Solving Technique:
NMOSFET DC Analysis
MOS Circuits
1. 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 cutoff
b. If VDS < VDS(sat), transistor is likely in
nonsaturation region
4. If initial assumption is proven incorrect, make
new assumption and repeat Steps 2 and 3.
Neamen
McGraw-Hill
Chapter 3-17
NMOS Common-Source Circuit
Neamen
McGraw-Hill
Chapter 3-19
Neamen
McGraw-Hill
Chapter 3-18
PMOS Common-Source Circuit
Neamen
McGraw-Hill
Chapter 3-20
5
9/2/2013
Load Line and Modes of Operation:
Neamen
McGraw-Hill
Chapter 3-21
MOS Small-Signal Amplifier
Neamen
McGraw-Hill
Chapter 3-22
Microelectronics
Circuit Analysis and Design
Donald A. Neamen
Chapter 4
Basic FET Amplifiers
Neamen
McGraw-Hill
Chapter 3-23
Neamen
McGraw-Hill
Chapter 3-24
6
9/2/2013
Simple NMOS Small-Signal
Equivalent Circuit
NMOS Transistor Small-Signal
Parameters
Values depends on Q-point
gm =
∂iD
∂vGS
=
id
v gs
g m = 2 K n (VGSQ − VTN ) = 2 K n I DQ
ro = ( ∂∂viDSD ) −1
ro = [λK n (VGSQ − VTN ) 2 ]−1 ≅ [λI DQ ]−1
Neamen
McGraw-Hill
Chapter 3-25
Channel Length Modulation:
Early Voltage
Neamen
McGraw-Hill
Chapter 3-26
Small-signal
AC
Av = Vo Vi = − g m (ro RD )
Neamen
McGraw-Hill
Chapter 3-27
Neamen
McGraw-Hill
Chapter 3-28
7
9/2/2013
Problem-Solving Technique:
MOSFET AC Analysis
Common-Source Configuration
DC analysis:
Coupling capacitor is assumed
to be open.
1. Analyze circuit with only the dc sources to
find quiescent solution. Transistor must be
biased in saturation region for linear
amplifier.
2. Replace elements with small-signal model.
3. Analyze small-signal equivalent circuit,
setting dc sources to zero, to produce the
circuit to the time-varying input signals only.
Neamen
McGraw-Hill
Chapter 3-29
AC analysis:
Coupling capacitor is assumed
to be a short. DC voltage
supply is set to zero volts.
Neamen
McGraw-Hill
Chapter 3-30
DC Load Line
Small-Signal Equivalent Circuit
Q-point near the middle
of the saturation region
for maximum symmetrical
output voltage swing,.
Small AC input signal for
output response to be
linear.
Ri
Av = Vo Vi = − g m (ro RD )(
)
Ri + RSi
Neamen
McGraw-Hill
Chapter 3-31
Neamen
McGraw-Hill
Chapter 3-32
8
9/2/2013
Common-Source Amplifier with
Source Resistor
for Common-Source with Source Resistor
Av =
Neamen
McGraw-Hill
Chapter 3-33
Neamen
Common-Source Amplifier with
Bypass Capacitor
McGraw-Hill
− g m RD
1 + g m RS
Chapter 3-34
NMOS Source-Follower
or Common Drain Amplifier
Small-signal equivalent circuit
Neamen
McGraw-Hill
Chapter 3-35
Neamen
McGraw-Hill
Chapter 3-36
9
9/2/2013
for Source Follower
Av =
Neamen
RS ro
Determining Output Impedance
NMOS Source Follower
Ri
)
1
+ RS ro Ri + RSi
gm
(
McGraw-Hill
RO =
Chapter 3-37
Neamen
McGraw-Hill
1
RS ro
gm
Chapter 3-38
Comparison of 3 Basic Amplifiers
Configuration
Voltage
Gain
Common
Source
Av > 1
Source
Follower
Av ≈ 1
Common
Gate
Av > 1
Neamen
Current
Gain
__
__
Ai ≈ 1
McGraw-Hill
Input
Output
Resistance Resistance
RTH
RTH
Low
Moderate
to high
Low
Moderate
to high
Chapter 3-39
10

Microelectronics Basic Structure of MOS Capacitor MOS Capacitor

Transcription

Similar documents

Microelectronics Differential Amplifier Intro. Differential Amplifier Intro.

Cortex™-M7, M4, M3, M1, M0 (ARM): Architektur