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Introduction to the Operational Amplifier. μ A 741 OP AMP. Schematic -- 741 OP AMP. 741 OP AMP – Package & Pin Layout. 2 Inverting Input 3 Non-Inverting Input 6 Output 7 + Voltage Supply V CC 4 – Voltage Supply V EE 1 and 5 -- Offset Null. Circuit Symbol for the OP AMP. - PowerPoint PPT Presentation
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ECE 201 Circuit Theory I 1
Introduction to the Operational Amplifier
μA 741 OP AMP
ECE 201 Circuit Theory I 2
Schematic -- 741 OP AMP
ECE 201 Circuit Theory I 3
741 OP AMP – Package & Pin Layout
•2 Inverting Input•3 Non-Inverting Input•6 Output•7 + Voltage Supply VCC
•4 – Voltage Supply VEE
•1 and 5 -- Offset Null
ECE 201 Circuit Theory I 4
Circuit Symbol for the OP AMP
Simplify to 3 terminals
ECE 201 Circuit Theory I 5
μA 741 OP AMP – Pin Identification
• 2 Inverting Input• 3 Non-Inverting Input• 6 Output
• 7 + Voltage Supply VCC
• 4 – Voltage Supply VEE
• 1 and 5 -- Offset Null
U1
741
3
2
4
7
6
51
For simplicity, use only pins 2, 3, and 6.
ECE 201 Circuit Theory I 6
Terminal Voltages
ECE 201 Circuit Theory I 7
Terminal Currents
ECE 201 Circuit Theory I 8
Voltage Transfer Characteristic
( )o p nv f v v
ECE 201 Circuit Theory I 9
( )o p nv A v v
A gain
10,000
20p n
A
v v mV
ECE 201 Circuit Theory I 10
Ideal OP AMP (Open Loop)
( )
0
o p n
in
p n
p n
v A v v
R
A
v v
i i
A
A = “open-loop” gain
ECE 201 Circuit Theory I 11
Connect Rf -- “Negative Feedback”
ECE 201 Circuit Theory I 12
Inverting Amplifier
ECE 201 Circuit Theory I 13
Analysis Using the Ideal OP AMP
0
i i is f n
v vn p
vsi
s Rsvoi
f Rf
“Virtual” ground
ECE 201 Circuit Theory I 14
Analysis continued
0n
f s
o s
f s
fo s
s
i
i i
v v
R R
Rv v
R
GND
ECE 201 Circuit Theory I 15
Non-Inverting Amplifier
ECE 201 Circuit Theory I 16
Analysis Using the Ideal OP AMP
1
p g
sn p g o
s f
s fo g
s
fo g
s
v v
Rv v v v
R R
R Rv v
R
Rv v
R
“Virtual Short