cmpe 118 mechatronics operational amplifiers (opamps) and comparators signal conditioning,...
Post on 21-Dec-2015
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![Page 1: CMPE 118 MECHATRONICS Operational Amplifiers (OpAmps) and Comparators Signal Conditioning, Buffering, Etc](https://reader031.vdocuments.net/reader031/viewer/2022032310/56649d5f5503460f94a401ab/html5/thumbnails/1.jpg)
CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Operational Amplifiers (OpAmps) and Comparators
Signal Conditioning, Buffering, Etc.
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Operational Amplifier
+
- Characteristics
Infinte GainDraws No Input Current
Difference Amplifier
V+ > V- then the output is driven in the Positive direction
V- > V+ then the output is driven in the Negative direction
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Operational Amplifier
+
- Characteristics
Infinte GainDraws No Input Current
![Page 4: CMPE 118 MECHATRONICS Operational Amplifiers (OpAmps) and Comparators Signal Conditioning, Buffering, Etc](https://reader031.vdocuments.net/reader031/viewer/2022032310/56649d5f5503460f94a401ab/html5/thumbnails/4.jpg)
CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
+
-
Vout
Vin
How do we use Op-Amps then?
Negative Feedback
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
The Golden Rules:Apply only when the op-amp is operated:
Within its listed specifications
In Negative Feedback
1) The Inputs Draw no Current
2) The inverting and Non-inverting inputsremain at the same voltage
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
The Golden Rules:Apply only when the op-amp is operated:
![Page 7: CMPE 118 MECHATRONICS Operational Amplifiers (OpAmps) and Comparators Signal Conditioning, Buffering, Etc](https://reader031.vdocuments.net/reader031/viewer/2022032310/56649d5f5503460f94a401ab/html5/thumbnails/7.jpg)
CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
+
- R1
R2
A
B
Vout Vin
Inverting Amplifier
Vout
R2 R1
-Vin =
Vout
Vin
R2
R1 = -
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
+
- R1
R2
A
B
Vout Vin
Inverting Amplifier
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
+
- R1
R2
A
B
Vout
Vin
Non-Inverting Amplifier
= Vin R1
Vout R1 + R2
= Vin R1
Vout R2 1 +
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
+
- R1
R2
A
B
Vout
Vin
Non-Inverting Amplifier
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
+
-
Vout
Vin
=
Non-Inverting Buffer
Vin Vout
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Vin
Source Resistance
True
PerceivedVin
+
- R1
R2
A
B
Vout
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
What Happens to the output if we tie the two inputs together?
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Input Offset Voltage
V
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Input Offset Voltage Specifications
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Effects of Input Offset Voltage
+ V
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Input Bias Current
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Input Bias Current Specifications
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Can We Correct for Input Bias Current?
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Does that fix the bias current problem?
Not Quite
The two bias currents are not exactly equal
This is the Input Offset Current
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Does that fix the bias current problem?
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Output Voltage Limitations
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Output Voltage Specifications
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
The Importance of Test Conditions“RL = 2k”
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Specifications that you shouldn’t use:
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Specifications that you shouldn’t use:
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
+
- R1
R2
A
B
Vout
Vin
What is the minimum values for R1 & R2 if Vout is driving a 10k load and we want to achieve a 3.3V output?
LM324
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Frequency Effects
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Large Signal Frequency Response
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
0 .00 0u 20 .0 0u 40 .0 0u 60 .0 0u 80 .0 0u 10 0 .0uTim e (s )
(V
)
10.00
9.000
8.000
7.000
6.000
5.000
4.000
3.000
2.000
1.000
0 .000
ou tp u t
in pu t*10
Slew Rate Effects
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
0 .00 0u 2 .00 0u 4 .00 0u 6 .00 0u 8 .00 0u 10 .0 0uTim e (s )
(V
)
10.00
9.000
8.000
7.000
6.000
5.000
4.000
3.000
2.000
1.000
0 .000
ou tp u t
in pu t*10
Extreme Slew Rate Effects
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
P a r a m e ter L M 3 2 4 L M 6 1 4 4 L M C 6 4 8 4 L M C 6 4 9 4In p u t O ffse t Vo ltag e 7 m V 3 .3 m V 3 .7 m V 6 .8 m VIn p u t B ia s C u rren t 2 5 0 n A 5 2 6 n A 4 p A 2 0 0 p AIn p u t O ffse t C u rre n t 5 0 n A 8 0 n A 2 p A 1 0 0 p AO u tp u t Vo lta g e H i @ 1 0 K 3 .5 V 4 .8 7 VO u tp u t Vo lta g e L o @ 1 0 K 0 .0 2 V 0 .0 5 VO u tp u t Vo lta g e H i @ 2 K 3 V 4 .8 V 4 .7 V 4 .7 VO u tp u t Vo lta g e L o @ 2 K 0 .1 3 0 .2 4 V 0 .2 4 VO u tp u t Vo lta g e H i @ 6 0 0 4 .2 4 V 4 .2 4 VO u tp u t Vo lta g e L o @ 6 0 0 0 .6 5 V 0 .6 5 VU n ity G a in B a n d w id th 1 M H z 6 M H z 1 .5 M H z 1 .5 M H zS lew R a te 0 .4 2 V /S 11 V /S 0 .6 3 V /S 0 .5 V /SIn p u t C o m m o n M o d e R a n g e 0 -3 .5 V 0 -5 V 0 -5 V 0 -5 VC o st @ 1 k $ 0 .0 8 8 $ 2 .8 0 $ 1 .3 9 $ 1 .5 9Te m p e ra tu re R a n g e 0 ° – 7 0 ° C -4 0 ° – 8 5 ° C -4 0 ° – 8 5 ° C -4 0 ° – 1 2 5 ° C
A Comparison of Some Op-Amps
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Questions?
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
What is This?
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
How might you use it?
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Without With
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
How do you achieve it?
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Eliminating the separate VREF
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
What’s going on?
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
Inverting Comparator Design ProcedureTrip point at 1.5V, 0.25V Hysterisis
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
The Non-Inverting configuration:
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
How does this circuit Behave?
R1=3k, R2=R3=1KVin sweeps from 0-5V
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CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS
How about this one?
Vin = 5 to -5V Sin
What are the thresholds?