Op&Amps&and&Signal&Condi5oning& - Harvey Mudd College · 2015. 2. 10. · • The ideal op amp is...

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Op Amps and Signal Condi5oning

E80 Spring 2015 Erik Spjut

5 wire diagram

2

Non-inverting input

Inverting input Output

Positive supply

Negative supply

Inverting and non-inverting inputs are often flipped in the schematic. Be sure you check.

Sample Op Amp Internals

"OpAmpTransistorLevel Colored Labeled" by Daniel Braun -‐ redrawn png file (from User:Omegatron), datasheet. Licensed under CC BY 2.5 via Wikimedia Commons -‐ hRp://commons.wikimedia.org/wiki/File:OpAmpTransistorLevel_Colored_Labeled.svg#mediaviewer/File:OpAmpTransistorLevel_Colored_Labeled.svg

For the curious. Not needed for E80

3

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Simulink Op Amp Model •  Rate limited integrator followed by a

range limit block. •  Ask Prof. Spjut if you ever need it.

For the curious. Not needed for E80

4

Simplified Real Op Amp Model

5

For the curious. Not needed

for E80

V

out= G V

+−V

−( )

•  The internally generated voltage is the gain times the difference of the input voltages.

•  The input impedance is very large. •  The output impedance is very small. •  The ideal op amp is derived by

assuming the gain approaches ∞, the output impedance approaches 0, and the input impedance approaches ∞.

TL081 Datasheet

See Figure 3

TA = 25°C

C2 = 3 pF

VCC± = ±15 V

105

104

103

102

10

1 M100 k10 k1 k

106

10 M

f − Frequency With Feed-Forward Compensation − Hz

1100

DIFFERENTIAL VOLTAGE AMPLIFICATIONvs

FREQUENCY WITH FEED-FORWARD COMPENSATION

−D

iffe

ren

tialV

olt

ag

eA

mp

lifi

cati

on

−V

/mV

AV

D

−750

−To

tal

Po

wer

Dis

sip

ati

on

−m

W

TA − Free-Air Temperature − °C

125

250

−50 −25 0 25 50 75 100

25

50

75

100

125

150

175

200

225VCC± = ±15 VNo SignalNo Load

TL084, TL085

TL082, TL083

TL081

TOTAL POWER DISSIPATIONvs

FREE-AIR TEMPERATURE

PD

−751

Volta

ge A

mpl

ifica

tion −

V/m

V

TA − Free-Air Temperature − °C125

1000

−50 −25 0 25 50 75 100

2

4

10

20

40

100

200

400

VCC± = ±15 VVO = ±10 VRL = 2 kΩ

LARGE-SIGNALDIFFERENTIAL VOLTAGE AMPLIFICATION

vsFREE-AIR TEMPERATURE

AVD −

Larg

e-Si

gnal

Diff

eren

tial

AVD

0°

45°

180°

135°

90°

11

f − Frequency − Hz10 M

106

10 100 1 k 10 k 100 k 1 M

101

102

103

104

105

DifferentialVoltageAmplification

VCC± = ±5 V to ±15 VRL = 2 kΩTA = 25°C

Phase Shift

LARGE-SIGNALDIFFERENTIAL VOLTAGE AMPLIFICATION

AND PHASE SHIFTvs

FREQUENCY

Volta

ge A

mpl

ifica

tion

AVD −

Larg

e-Si

gnal

Diff

eren

tial

AVD

Phas

e Sh

ift

TL081, TL081A, TL081B, TL082, TL082A, TL082BTL084, TL084A, TL084B

www.ti.com SLOS081H –FEBRUARY 1977–REVISED JANUARY 2014

Figure 11. Figure 12.

Figure 13. Figure 14.

Copyright © 1977–2014, Texas Instruments Incorporated Submit Documentation Feedback 9

Product Folder Links: TL081 TL081A TL081B TL082 TL082A TL082B TL084 TL084A TL084B

TL081, TL081A, TL081B, TL082, TL082A, TL082BTL084, TL084A, TL084BSLOS081H –FEBRUARY 1977–REVISED JANUARY 2014 www.ti.com

Electrical CharacteristicsVCC± = ±15 V (unless otherwise noted)

TL081C TL081AC TL081BC TL081ITL082C TL082AC TL082BC TL082ITESTPARAMETER TA(1) UNITTL084C TL084AC TL084BC TL084ICONDITIONS

MIN TYP MAX MIN TYP MAX MIN TYP MAX MIN TYP MAX

25°C 3 15 3 6 2 3 3 6Input offset VO = 0,VIO mVvoltage RS = 50 Ω Full range 20 7.5 5 9

Temperaturecoefficient of VO = 0,αVIO Full range 18 18 18 18 μV/°Cinput offset RS = 50 Ωvoltage

25°C 5 200 5 100 5 100 5 100 pAInput offsetIIO VO = 0current(2) Full range 2 2 2 10 nA

25°C 30 400 30 200 30 200 30 200 pAInput biasIIB VO = 0current(2) Full range 10 7 7 20 nA

Common- –12 –12 –12 –12VICR mode input 25°C ±11 ±11 ±11 ±11 Vto 15 to 15 to 15 to 15voltage range

RL = 10 kΩ 25°C ±12 ±13.5 ±12 ±13.5 ±12 ±13.5 ±12 ±13.5MaximumVOM peak output RL ≥ 10 kΩ ±12 ±12 ±12 ±12 V

Full rangevoltage swing RL ≥ 2 kΩ ±10 ±12 ±10 ±12 ±10 ±12 ±10 ±12

Large-signal 25°C 25 200 50 200 50 200 50 200differential VO = ±10 V,AVD V/mVvoltage RL ≥ 2 kΩ Full range 15 15 25 25amplification

Unity-gainB1 25°C 3 3 3 3 MHzbandwidth

Inputri 25°C Ω1012 1012 1012 1012resistance

Common- VIC = VICRmin,CMRR mode VO = 0, 25°C 70 86 75 86 75 86 75 86 dB

rejection ratio RS = 50 Ω

Supply- VCC = ±15 Vvoltage to ±9 V,kSVR 25°C 70 86 80 86 80 86 80 86 dBrejection ratio VO = 0,(ΔVCC±/ΔVIO) RS = 50 Ω

Supply VO = 0,ICC current (each 25°C 1.4 2.8 1.4 2.8 1.4 2.8 1.4 2.8 mANo loadamplifier)

VO1/VO Crosstalk AVD = 100 25°C 120 120 120 120 dB2 attenuation

(1) All characteristics are measured under open-loop conditions with zero common-mode voltage, unless otherwise specified. Full range forTA is 0°C to 70°C for TL08_C, TL08_AC, TL08_BC and −40°C to 85°C for TL08_I.

(2) Input bias currents of an FET-input operational amplifier are normal junction reverse currents, which are temperature sensitive, asshown in Figure 17. Pulse techniques must be used that maintain the junction temperature as close to the ambient temperature aspossible.

4 Submit Documentation Feedback Copyright © 1977–2014, Texas Instruments Incorporated


TL081, TL081A, TL081B, TL082, TL082A, TL082BTL084, TL084A, TL084BSLOS081H –FEBRUARY 1977–REVISED JANUARY 2014 www.ti.com

Electrical CharacteristicsVCC± = ±15 V (unless otherwise noted)

TL081C TL081AC TL081BC TL081ITL082C TL082AC TL082BC TL082ITESTPARAMETER TA(1) UNITTL084C TL084AC TL084BC TL084ICONDITIONS

MIN TYP MAX MIN TYP MAX MIN TYP MAX MIN TYP MAX

25°C 3 15 3 6 2 3 3 6Input offset VO = 0,VIO mVvoltage RS = 50 Ω Full range 20 7.5 5 9

Temperaturecoefficient of VO = 0,αVIO Full range 18 18 18 18 μV/°Cinput offset RS = 50 Ωvoltage

25°C 5 200 5 100 5 100 5 100 pAInput offsetIIO VO = 0current(2) Full range 2 2 2 10 nA

25°C 30 400 30 200 30 200 30 200 pAInput biasIIB VO = 0current(2) Full range 10 7 7 20 nA

Common- –12 –12 –12 –12VICR mode input 25°C ±11 ±11 ±11 ±11 Vto 15 to 15 to 15 to 15voltage range

RL = 10 kΩ 25°C ±12 ±13.5 ±12 ±13.5 ±12 ±13.5 ±12 ±13.5MaximumVOM peak output RL ≥ 10 kΩ ±12 ±12 ±12 ±12 V

Full rangevoltage swing RL ≥ 2 kΩ ±10 ±12 ±10 ±12 ±10 ±12 ±10 ±12

Large-signal 25°C 25 200 50 200 50 200 50 200differential VO = ±10 V,AVD V/mVvoltage RL ≥ 2 kΩ Full range 15 15 25 25amplification

Unity-gainB1 25°C 3 3 3 3 MHzbandwidth

Inputri 25°C Ω1012 1012 1012 1012resistance

Common- VIC = VICRmin,CMRR mode VO = 0, 25°C 70 86 75 86 75 86 75 86 dB

rejection ratio RS = 50 Ω

Supply- VCC = ±15 Vvoltage to ±9 V,kSVR 25°C 70 86 80 86 80 86 80 86 dBrejection ratio VO = 0,(ΔVCC±/ΔVIO) RS = 50 Ω

Supply VO = 0,ICC current (each 25°C 1.4 2.8 1.4 2.8 1.4 2.8 1.4 2.8 mANo loadamplifier)

VO1/VO Crosstalk AVD = 100 25°C 120 120 120 120 dB2 attenuation

(1) All characteristics are measured under open-loop conditions with zero common-mode voltage, unless otherwise specified. Full range forTA is 0°C to 70°C for TL08_C, TL08_AC, TL08_BC and −40°C to 85°C for TL08_I.

(2) Input bias currents of an FET-input operational amplifier are normal junction reverse currents, which are temperature sensitive, asshown in Figure 17. Pulse techniques must be used that maintain the junction temperature as close to the ambient temperature aspossible.

4 Submit Documentation Feedback Copyright © 1977–2014, Texas Instruments Incorporated


10 M1 M100 k10 k1 k100f − Frequency − Hz

VOM

− M

axim

um P

eak

Out

put V

olta

ge −

V

0

±2.5

±5

±7.5

±10

±12.5

±15

See Figure 2TA = 25°CRL = 2 kΩ

VCC± = ±10 V

VCC± = ±5 V

MAXIMUM PEAK OUTPUT VOLTAGEvs

FREQUENCY

V OM

VCC± = ±15 V

RL = 10 kΩTA = 25°CSee Figure 2

±15

±12.5

±10

±7.5

±5

±2.5

0

VOM

− M

axim

um P

eak

Out

put V

olta

ge −

V

f − Frequency − Hz100 1 k 10 k 100 k 1 M 10 M

MAXIMUM PEAK OUTPUT VOLTAGEvs

FREQUENCY

V OM

VCC± = ±5 V

VCC± = ±10 V

VCC± = ±15 V

TL081, TL081A, TL081B, TL082, TL082A, TL082BTL084, TL084A, TL084B

www.ti.com SLOS081H –FEBRUARY 1977–REVISED JANUARY 2014

Typical CharacteristicsData at high and low temperatures are applicable only within the rated operating free-air temperature ranges of the various

devices.

Table of GraphsFigure

vs Frequency Figure 5, Figure 6, Figure 7vs Free-air temperature Figure 8VOM Maximum peak output voltage vs Load resistance Figure 9vs Supply voltage Figure 10

Large-signal differential voltage vs Free-air temperature Figure 11amplification vs Load resistance Figure 12AVDDifferential voltage amplification vs Frequency with feed-forward compensation Figure 13

PD Total power dissipation vs Free-air temperature Figure 14vs Free-air temperature Figure 15ICC Supply current vs Supply voltage Figure 16

IIB Input bias current vs Free-air temperature Figure 17Large-signal pulse response vs Time Figure 18

VO Output voltage vs Elapsed time Figure 19CMRR Common-mode rejection ratio vs Free-air temperature Figure 20Vn Equivalent input noise voltage vs Frequency Figure 21THD Total harmonic distortion vs Frequency Figure 22

Figure 5. Figure 6.

Copyright © 1977–2014, Texas Instruments Incorporated Submit Documentation Feedback 7


6

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Ideal Op Amp Model •  Input impedance: ∞Ω •  Output impedance: 0Ω •  With negative feedback, gain so high

that V+ = V–

7

Opera5onal Amplifier •  Can be configured to perform mathematical

operations on a signal. !  Multiply by a constant (change gain) !  Change sign !  Add two or more signals !  Subtract one signal from another !  Integrate a signal !  Differentiate a signal !  Many others

8

Unity Gain Buffer

9

•  Your go-to circuit. It solves many problems. •  Analyze circuit. •  Draws no current at input (ideal model).

•  Provides needed current at output (ideal model).

•  Transfers voltage with no circuit loading.

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Non-‐Inver5ng

10

•  High impedance input, great for measuring voltages

•  Gains ≥1

•  Do you see the voltage divider? •  Analyze circuit.

V

out= 1+

Rf

R1

⎛

⎝⎜

⎞

⎠⎟Vin

Inver5ng

11

V

out= −

Rf

R1

Vin

•  Input impedance is R1 (ideal model). •  Flips sign (or phase) of input. •  Full gain range

•  Analyze circuit.

Inver5ng Summing Amp

12

V

out= −

Rf

R1

V1+

Rf

R2

V2+

Rf

R3

V3

⎛

⎝⎜

⎞

⎠⎟

•  How would you sum three signals? •  How would you average three signals? •  What is the input impedance? •  Analyze circuit. •  Non-inverting summer exists.

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General Impedance Model

13

V

out= −

Z1

Z2

Vin

•  Analyze circuit. •  Do you see the voltage divider? •  What is the input impedance?

Integrator

14

V

out= −

Z1

Z2

Vin= −

1jωC

1

R1

Vin= − 1

jR1C

1ω

Vin

•  What is the time-domain version? •  How do you set initial condition? •  How do you reset?

Differen5ator

15

Vout

= −Z

1

Z2

Vin= −

R1

1jωC

1

Vin= − jR

1C

1ω( )Vin

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Filters – LP, HP

16

Vout

Vin

= H( jω ) = −R

1R

2

1+ jωR1C

1

Vout

Vin

= H( jω ) = −jωR

1C

2

1+ jωR2C

2

Filters – BP

17

H( jω ) =− jωR

2C

1

1+ jωR1C

1( ) 1+ jωR2C2( )

A Step Up – Sallen & Key

18

Vout

Vin

=Z

3Z

4

Z1Z

2+ Z

3Z

1+ Z

2( ) + Z3Z4

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Difference Amplifier

19

V

out=

R4

R3+ R

4

⎛

⎝⎜

⎞

⎠⎟

R1+ R

2

R1

⎛

⎝⎜

⎞

⎠⎟V2 −

R2

R1

⎛

⎝⎜

⎞

⎠⎟V1

R3 = R1 R4 = R2 V

out=

R2

R1

V2−V

1( )If and then

Instrumenta5on Amplifier

20

V

out−V

ref= 1+

2R1

Rgain

⎛

⎝⎜

⎞

⎠⎟

R3

R2

Vnon−inv

−Vinv( )

•  Set gain with Rgain. •  Vref must be a low-impedance source. •  Never make one. Use a commercial one.

Transimpedance Amp

21

V

out= iR

f •  If Vout has the wrong sign, flip the diode. •  The far side of the photodiode can be tied

to Vbias instead of ground.

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Logarithmic Amp

22

V

out= −V

Tln

Vin

isR

1

⎛

⎝⎜

⎞

⎠⎟

VT and is are diode properties. •  Thermal voltage •  Saturation current

Exponen5al Amp

23

V

out= −R

1isexp

Vin

VT

⎛

⎝⎜

⎞

⎠⎟

VT and is are diode properties. •  Thermal voltage •  Saturation current

What Does It Do?

24

•  What does the first voltage divider do? •  Can you find the unity gain buffer? •  Where is the instrumentation amp? •  Can you find the modified difference amp? •  What are G and K? •  Don’t use a circuit you don’t understand.

Vout = G(V2 −V4 )+ K

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LabVIEW File Naming Convention: Your file name should be (Last Name)_(First Initial)_A(Assignment Number)_S(Section Number).(vi or llb). For example, if I were Greg Lake in Section 4 and I was turning in Assignment 3, my file would be named Lake_G_A3_S4.llb. If your file does not have the correct naming convention, it will not be graded.

Professors have asked that you submit lab reports as PDF files. There are too many Mac/Win formatting battles to submit Word files.

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Op&Amps&and&Signal&Condi5oning& - Harvey Mudd College · 2015. 2. 10. · • The ideal op amp is...

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