op amp application
TRANSCRIPT
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OP-AMP APPLICATIONS
AGENDA:
Cascaded OP-AMP
Summing Amplifier Difference Amplifier
Voltage Buffer
Integrator Differentiator
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REVIEW:
1
2
R R AV
iO V
R
RV
1
2
1 R Rin OL
CL specsout
CL
OL
specsout out
A A R
A A
R R )(
)(
1
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REVIEW:
1
1
2
R
R AV
1
1
2
R RV V iO
)( specsin
CL
OLin R
A A R
)( specsout
OL
CL
out R A
A
R
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4
2
2
2
in
i
f
O V R
RV
in
i
f
O V R
RV 1
Therefore the output voltage is equal to:
in
ii
f f
O V R R
R RV
2
2and the voltage gain is equal to:
2
2
ii
f f
V R R
R R A
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2
2
1
1
2
2
1
1
21;*
)(0;*
i f
i f
O
f
Oii
f
V R RV
R RV
R
V V
R
V V
R
V V
I I I Anodeat
ground virtual V V V
more
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To avo id offs et errors place a R = R1||R2 ||RF to g roun d from the
non- inver t ing inp ut .
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VOLTAGE BUFFER
The advantage of this
connection is that theload connected across oneoutput has no (or little)effect on the otheroutput. The outputs arebuffered or isolated fromeach other.
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I2
I3
y
1.
11
0
;*
23
32
2
2
32
23
2
2
32
32
2
32
eqn R R
RV V
R
V
R R
R R
V
R
V
R RV
R
V
R
V V
I I
ynodeat
i y
i
y
i y
y yi
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IF
I1
x
2.11
;*
1
1
1
1
1
1
eqn RV
RV
R RV
R
V V
R
V V I I
xnodeat
F
Oi
F
x
F
xO xi
F
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IF
I1
x
2.11
1
1
1
eqn R
V
R
V
R RV
F
Oi
F
x
1
1
1
1
23
32
1
1
1
1
23
32
1
1
123
32
11
2.1.*
;;;sin
R
V
R R
R R
R R
RV
R
V
RV
RV
R R R R
R R RV
R
V
R
V
R R R R
RV
eqneqn substitute
V V V V V V ce
i
F
F
x
i
F
O
F
Oi
F
F
x
i
F
Oi
F x
i
x y y
1
1
1
1
23
32
R
RV
R
R R
R R
RV V F
i F
x
iO
1.
23
32 eqn
R R
RV V i y
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If RF
= R3
and R2 = R1
12
1
ii F
O V V R RV
more
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IC
Ii
X
dt vC R
V
dt
V d C
R
V
V but
dt
V V d C
R
V V
dt
dvC irecall
I I
X nodeat
iO
Oi
Oi
C C
C i
1
1
1
1
side bothintegrate
;
0
;
;
;
;
dt vC R
V iO
1
1
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IF
IC
X
dt
V d C RV
R
V
dt
V d C
V but
R
V V
dt
V V d C
dt
dvC irecall
I I
X nodeat
i F O
F
Oi
F
Oi
C C
F C
;
0
;
;
;
;
dt
V d
C RV i
F O
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THANK YOU!!! THANK YOU!!!
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1. Calculate the output voltage of a cascaded circuit if the first
stage is a non-inverting amplifier and the 2nd and 3rd is aninverting op-amp having the following values for A1: Vin =
20μV, RF1=510KΩ and Ri1=18KΩ; for A2: RF2=680KΩ,
Ri2=22KΩ; for A3: RF3=750KΩ, Ri3=33KΩ. (Vo = 412 mV)
2. Calculate the output voltage for inverting summing amplifier having input resistances of 47KΩ and 12KΩ with an input
voltages of 40mV rms and 20 mV rms respectively. Use
feedback resistor value of 470KΩ. (-1.18V)
3. For a difference amplifier if RF=300KΩ with input resistor
value of R1=150KΩ(one terminal connected to inverting input)and R2=10KΩ(one terminal connected to non-inverting input)
and R3=10KΩ, determine output voltageVo.(Vo = -2.5V)
EXAMPLES: