chapter10 2017 [호환 모드] - HANSUNGkwangho/lectures/EE_Lab/2017/...Dept. Electronics and Information Eng. Vacuum Tube Op-Amps First op amps built in 1930’s-1940’s Technically

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Lab. 10 OP Amp의 기초 및 연산회로

Dept. Electronics and Information Eng. 2

이 실험의 목표

OP Amp의 특성 및 응용 OP Amp란 무엇인가? OP Amp를 구성하는 parameters Inverting Amplifier Non-Inverting Amplifier OP Amp를 이용한 가산회로

OP Amp를 이용한 감산회로

Dept. Electronics and Information Eng.

Vacuum Tube Op-Amps

First op amps built in 1930’s-1940’s Technically feedback amplifiers due to

only having one useable input

Used in WWII to help how to strike military targets Buffers, summers, differentiators,

inverters

Took ±300V to ± 100V to power

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Solid State Discrete Op-Amps

Solid state op amps invented in 1960’s Possible due to invention of silicon

transistors and the IC Chip and discrete parts

Reduced power input to ±15V to ±10V Packaging in small black boxes allowed

for integration with a circuit

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Monolithic Integrated Circuit Op-Amp

First created in 1963 μA702 by Fairchild Semiconductor

μA741 created in 1968 Became widely used due to its ease of use 8 pin, dual in-line package (DIP)

Further advancements include use of field effects transistors (FET), greater precision, faster response, and smaller packaging

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Introduction

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(a) A µA741 integrated circuit has eight connecting pins. (b) The correspondence between the circles pin numbers of the

integrated circuit and the nodes of the operational amplifier.


Introduction

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Nulling Procedure for Output Voltage The output voltage should equal 0 V. But, there will be a small error-voltage component (offset voltage)

presented in

OP Amp Parameters

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oV

oV

GND GND


How can we correct for this offset voltage? Offset voltage of most IC op amps can be manually adjusted by

adding a potentiometer. A potentiometer is connected across the offset null terminals with

the supply voltage connected to the adjustable center tap.

(Adjust for zero output at circuit needed a high precision)(External potentiometer)

OP Amp Parameters

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ccV

(1)(5)

-V


Ideal Audio Amp

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SS

RRLout

L

inS

inL Avv

RRRA

RRRv

outin

0


Practical OP Amp

Ideal OP Amp

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Ideal OP Amp


OP Amp Operation

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OP Amp Operation

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[ Inverting and non-inverting amplifiers ]


Inverting Amplifier

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Inverting Amplifier

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2

1

Ov

I

v RAv R


Inverting Amplifier

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Non-Inverting Amplifier

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1

1

,in i

o v i v in

v v vv A v A v v

Since 1

11 2

,oRv v

R R

1

1 2

11

o

in

v

vRv

A R R

1 2

1

o

in

v R Rv R

for large gain Av


Pspice Model:

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Inverting Amplifier


Voltage Follower

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Summing Amplifier

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1 2out T f fV I R I I R

Since 1 21 2

1 2

, ,in inV VI IR R

1 21 2

f fout in in

R RV V V

R R


Summing Amplifier

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Difference Amplifier

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Use superposition, set V2 = 0, solve for Vo : Inverting amp set V1 = 0, solve for Vo : Non-inverting amp



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201 1

1

RV VR



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2 402 2

1 3 4

1 R RV VR R R

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3 4

R VR R



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Add the two results V0 = V01 + V02

If R1 = R2 = R3 = R4

1

21

43

4

1

22 1

RRV

RRR

RRVVo

2 1 2 111 1 12oV V V V V



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[ Design of difference amplifiers ]For Vo = V2 - V1Set R2 = R1 = R, and set R3 = R4 = R

For Vo = 3V2 - 2V1Set R1 = R, R2 = 2R, then 3[R4/(R3+R4)] = 3Set R3 = 0


Application of OP Amp

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Power Supply Terminals

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Actual wiring from power supply to op amp

All voltage measurements are made with respect to power supply common !


Op-Amp Biasing

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+

-

+Vs

-Vs

0.1μF

0.1μF

2

34

7

6741

+Vs

-Vs

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chapter10 2017 [호환 모드] - HANSUNGkwangho/lectures/EE_Lab/2017/...Dept. Electronics and Information Eng. Vacuum Tube Op-Amps First op amps built in 1930’s-1940’s Technically