Download chapter 10 _Analog intergrated circuits

Chapter 10 Analog Integrated
Circuits and its application
Introduction
The 741 Op-Amp Circuit
The ideal Op Amp
The inverting configuration
The noninverting configuration
Integrator and differentiator
Other operation application
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Introduction
信号的提取：传感器、接收器或信号发生器，通常信号比较微弱，且易受
干扰，甚至与噪声的幅度相当。
信号预处理：信号的分离与放大（隔离、滤波与阻抗变换）
信号的加工：信号的运算、转换和比较等。一般再经功放才能驱动负载，
或者经A/D转换到PC机
信号的执行：一般为CPU（MCU，DSP，PC）
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Content
Part 1. The 741 Op-Amp Circuit and analysis.
Part 2. Analog integrated circuits’ application
_ the application of operational amplifier
_ the application of comparer circuits
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Part I:
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Analog ICs include operational amplifiers, analog
multipliers, A/D converters, D/A converters, PLL,
etc.
A complete op amp is realized by combining
analog circuit building blocks.
The bipolar op-amp has the general purpose
variety and is designed to fit a wide range of
specifications.
The terminal characteristics is nearly ideal.
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The 741 Op-Amp Circuit
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Structure
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“化整为零”：划分偏置电路、输入级、中间级和
输出级
“分析功能”：分别分析各部分的结构形式及特
点
“统观整体” ：研究各部分电路之间的联系
“定量估算”：必要时做定量分析
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General Description
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24 transistors, few resistors and only one
capacitor
Two power supplies
Short-circuit protection
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The Input Stage
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The input stage consists of transistors Q1
through Q7.
Q1-Q4 is the differential version of CC and CB
configuration.
High input resistance.
Current source (Q5-Q7) is the active load of input
stage. It not only provides a high-resistance load
but also converts the signal from differential to
single-ended form with no loss in gain or
common-mode rejection.
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The Intermediate Stage
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The intermediate stage is composed of Q16, Q17
and Q13B.
Common-collector configuration for Q16 gives this
stage a high input resistance as well as reduces
the load effect on the input stage.
Common-emitter configuration for Q17 provides
high voltage gain because of the active load Q13B.
Capacitor Cc introduces the miller compensation
to insure that the op amp has a very high unitgain frequency.
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The Output Stage
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The output stage is the efficient circuit called class AB
output stage.
Voltage source composed of Q18 and Q19 supplies the
DC voltage for Q14 and Q20 in order to reduce the
cross-over distortion.
Q23 is the CC configuration to reduce the load effect on
intermediate stage.
Short-circuit protection circuitry
 Forward protection is implemented by R6 and Q15.
 Reverse protection is implemented by R7, Q21,
current source(Q24, Q22) and intermediate stage.
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The Output Stage
(a) The emitter follower is a class A output stage. (b) Class B output stage.
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The Output Stage
Wave of a class B output stage fed with
an input sinusoid.
Positive and negative cycles are unable
to connect perfectly due to the turn-on
voltage of the transistors.
This wave form has the nonlinear
distortion called crossover distortion.
To reduce the crossover distortion can
be implemented by supplying the constant
DC voltage at the base terminals.
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The Output Stage
QN and QP provides the
voltage drop which equals to the
summer of turn-on voltages of
QN and QP.
This circuit is call Class AB
output stage.
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The Biasing Circuits
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Reference current is generated by Q12, Q11 and
R5.
Wilder current provides biasing current in the
order of μA.
Double-collector transistor is similar to the twooutput current mirror. Q13B provides biasing
current for intermediate stage, Q13A for output
stage.
Q5, Q6 and Q7 is composed of the current source
to be an active load for input stage.
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The Ideal Op Amplifier
symbol for the op amp
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The Ideal Op Amplifier
uo
o
uP  uN
The op amp shown connected to dc power supplies.
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Characteristics of the Ideal Op
Amplifier
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Differential input resistance is infinite.
Differential voltage gain is infinite.
CMRR is infinite.
Bandwidth is infinite.
Output resistance is zero.
Offset voltage and current is zero.
a)
b)
No difference voltage between
inverting and noninverting terminals.
No input currents.
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Ideal Op amplifier works at linear region
uo = Aod （ uN - uP ）
u
1. Differential input voltage is zero N
u
P
uN = uP
Virtual short circuit
feedback
iN
+A
od
iP
-
2. Input current is zero
iN = iP = 0
Virtual disconnect circuit
Working at linear region →
circuit with negative feedback
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u
o
Ideal Op amplifier works at nonlinear region
uo ≠ Aod （ u+ - u- ）
1. Vo have only two value
uo
uo = + UOPP when u+> u-
uo = - UOPP when u+ < u-
o
uP  uN
Virtual short circuit doesn’t exsist
2. i+ = i- =0
Virtual disconnect-circuit
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Equivalent Circuit of the Ideal Op
Amp
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The Inverting Configuration
Virtual short
circuit.
vo
v2  v1   0
A
Virtual
disconnect-circuit
i  i  0
Virtual ground: that is, having zero voltage but not physically
connected to ground
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The Inverting Configuration
vo
closed - loop gain : G 
vI
The inverting closed-loop configuration.
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The Inverting Configuration
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Effect of finite open-loop gain
vo
 R2 / R1
G 
vI 1  (1  R2 / R1 ) / A
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The Inverting Configuration
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Shunt-shunt negative feedback
Closed-loop gain depends entirely on passive
components and is independent of the op
amplifier.
Engineer can make the closed-loop gain as
accurate as he wants as long as the passive
components are accurate.
Exercises: example 2.2
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Example2.2
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Homework:
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May 27th, 2009
2.8; 2.22
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The Non-inverting Configuration
The noninverting configuration.
Series-shunt negative feedback.
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The Noninverting Configuration
Effect of finite
open-loop gain
1  R2 / R1
G
1  R2 / R1
1
A
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The Voltage follower
(a) The unity-gain buffer or follower amplifier.
(b) Its equivalent circuit model.
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The Weighted Summer
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The Weighted Summer
Ra Rc
Ra Rc
Rc
Rc
vo  v1 ( )( )  v2 ( )( )  v3 ( )  v4 ( )
R1 Rb
R2 Rb
R3
R4
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R2 // R3 // R4
R1 // R3 // R4
R2 // R1 // R4
uP 
uI 1 
uI 2 
uI 3
R1  R2 // R3 // R4
R2  R1 // R3 // R4
R3  R2 // R1 // R4
Rf
R2 // R3 // R4
R1 // R3 // R4
R2 // R1 // R4
uo  (1 
)(
uI 1 
uI 2 
uI 3 )
R R1  R2 // R3 // R4
R2  R1 // R3 // R4
R3  R2 // R1 // R4
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Example 2.6: A Single Op-Amp
Difference Amplifier
Linear amplifier.
Theorem of linear
Superposition.
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A Single Op-Amp Difference
Amplifier
Application of superposition
Inverting configuration
R2
vo1   vI 1
R1
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A Single Op-Amp Difference
Amplifier
Application of superposition.
Noninverting configuration.
R2
R4
vo 2  (1  )(
）vI 2
R1 R4  R3
vo  vo1  vo 2
R4 R2
R2
vI 2  vI 1 
if

, vo 
R3 R1
R1
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Integrators
The inverting configuration with general impedances in
the feedback and the feed-in paths.
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The Inverting Integrators
The Miller or inverting integrator.
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Frequency Response of the integrator
Vo s 
1
1


Vi s 
sCR
jCR
Vo
1

Vi CR
  90
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The op-amp Differentiator
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The op-amp Differentiator
  90
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Frequency response of a differentiator with a time-constant RC.
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Practical op-amp Differentiator
disadvantages：
1 )输入电压的阶跃变化和外界的脉冲干
扰，会使集成运放进入非线性区，出现阻
塞现象。
2) 反馈网络为滞后环节，它与集成运放
内部的滞后环节相叠加易于满足自激振荡
的条件。
R1：限制输入电流，也就限制了R中的电
流。DZ1（2）：稳压二极管限制了输出电
压保证了放大管工作在线性区，防止了阻
塞。C1：相位补偿作用，提高电路的稳
定性。
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Logarithm operation
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Exponential operation
uBE  uI
iR  iE  I S e
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UT
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Instrumentation Amplifier
UA＝UI1，UB＝UI2
uI1  uI 2 
R2
(uo1  uo 2 )
2 R1  R2
2 R1
uo1  uo 2  (1 
)( uI 1  uI 2 )
R2
Output voltage：
uo  
Rf
R
(uo1  uo 2 )
Rf
2 R1

(1 
)( uI 1  uI 2 )
R
R2
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Integrated Instrumentation Amplifier
三、集成仪表用放大器
6连7，增益为1
2连6和7，增益为10
3连6和7，增益为100
5连6/4连7，增益为1000
INA102
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exercises:
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Homework:
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June 3rd, 2009
2.36; 2.44; 2.61; 2.65
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