ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R.. ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R.. ELECTRICAL ENGINEERING:
Trang 1ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Chapter 11 Amplifiers:
Specifications and External Characteristics
Trang 2ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Chapter 11
Amplifiers:
Specifications and External Characteristics
1 Use various amplifier models to
calculate amplifier performance for given sources and loads.
2 Compute amplifier efficiency.
Trang 3ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
3 Understand the importance of input
various amplifier applications.
6 Understand linear and nonlinear
distortion in
amplifiers.
Trang 4ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
7 Specify the pulse-response parameters of
amplifiers.
8 Work with differential amplifiers and specify
common-mode rejection requirements.
9 Understand the various sources of dc offsets and
design balancing circuits.
Trang 5ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 6BASIC AMPLIFIER
CONCEPTS
Ideally, an amplifier produces an
output signal with identical
waveshape as the input signal, but with a larger amplitude.
t A v t
Trang 7ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 8Inverting versus Noninverting
Amplifiers
Inverting amplifiers have negative
voltage gain, and the output
waveform is an inverted version of
the input waveform Noninverting
amplifiers have positive voltage gain.
Trang 9ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 10Voltage-Amplifier
Model
Trang 11ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Current Gain
i
o i
i i
L o
i
o i
R
R A
R v
R
v i
i
Trang 12ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
i
v i
i
o o
i
o
R
R A
A
A I
V
I
V P
P
Trang 13ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 16ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 17Simplified Models for
The overall voltage gain is the product
of the gains of the separate stages.
The input impedance is that of the first stage, and the output impedance is that
of the last stage.
Trang 18ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 20POWER SUPPLIES AND
EFFICIENCY
B BB A
AA
s V I V I
Trang 21ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 24Current-Amplifier
Model
A isc is the current gain of the
amplifier with the output short circuited.
Trang 25ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 28Transconductance-Amplifier Model
i
o m
Trang 29ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 31Amplifier Model
Transresistance-i
o m
i
v
oc
Open circuit the output terminals and
analyze the circuit to determine R moc
Trang 32ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 34IMPORTANCE OF AMPLIFIER IMPEDANCES IN VARIOUS
APPLICATIONS
Some applications call for amplifiers
with high input (or output) impedance while others call for low input (or
output) impedance.
Other applications call for amplifiers that have specific input and/or output impedances.
Trang 35ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 37The proper classification of a given amplifier depends on the ranges of source and load impedances with which the amplifier is used.
Trang 38ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
FREQUENCY RESPONSE
i
o v
A
V V
Trang 39ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
30 1
0
15 10
A
V V
Trang 40ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 45LINEAR WAVEFORM
DISTORTION
If the gain of an amplifier has a
different magnitude for the various
frequency components
of the input signal, a form of distortion
known as amplitude distortion
occurs.
Trang 46ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 48ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 49Requirements for
Distortionless Amplification
To avoid linear waveform distortion, an amplifier should have constant gain
magnitude and a phase
response that is linear versus frequency for the range of frequencies contained in the input signal.
Trang 50ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 52PULSE RESPONSE
Trang 53ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 54Rise Time
B
t r 0 . 35
Trang 55ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 57% 100 tilt
P P
For small amounts
of tilt, f T
L
200 tilt
percentage
Trang 58ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
TRANSFER CHARACTERISTIC AND NONLINEAR DISTORTION
The transfer characteristic is a plot of instantaneous output amplitude versus instantaneous input amplitude.
Curvature of the transfer characteristic results in
nonlinear distortion.
Trang 59ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 61V V
D
Trang 62ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Total Harmonic Distortion (THD)
Total harmonic distortion is a
specification that indicates the degree
of nonlinear distortion produced by an amplifier.
Trang 63ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 64DIFFERENTIAL AMPLIFIERS
A differential amplifier has two input
terminals: an
inverting input and a noninverting input.
Ideally, a differential amplifier produces
an output that is proportional to the
difference between two input signals.
2
1 i i
id v v
v v o A d v id
Trang 65ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 67ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 68o A v A v
cm
log 20
CMRR
A
A d
Trang 69ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Trang 72OFFSET VOLTAGE,
BIAS CURRENT, AND
OFFSET CURRENT
Trang 73ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.
Real differential amplifiers suffer from imperfections that can be modeled by several
dc sources: two bias-current sources,
an offset current source, and an offset voltage source The effect of these
sources is to add a (usually
undesirable) dc term to the ideal
output.
Trang 74ELECTRICAL ENGINEERING: PRINCIPLES AND APPLICATIONS, Third Edition, by Allan R Hambley, ©2005 Pearson Education, Inc.