Module 2: Op Amps Introduction and Ideal Behavior

67 Pages·2014·0.87 MB·English

by  Josie Giles

Module 2: Op Amps
Introduction and Ideal
Behavior
Dr. Bonnie H. Ferri
Professor and Associate Chair
School of Electrical and
Computer Engineering
Introduce Op Amps and examine ideal behavior
School of Electrical and Computer Engineering
Lesson Objectives
 Introduce Operational Amplifiers
 Describe Ideal Op Amp Behavior
 Introduce Comparator and Buffer Circuits
2
Operational Amplifiers (Op Amps)
+V
s
v Specialized circuit made up of transistors,
+
+
v resistors, and capacitors fabricated on an
o
integrated chip
v
- -
-V
s
Uses:
 Amplifiers
 Active Filters
 Analog Computers
3
Op Amps in Circuits
Symbol:
+V
s
v
+
+ +
v v +V
o - s
v v
- - + v
o -
-V
-V s
s
V = 10V, 15V
s
 Active Element: has its own power supply
 Symbol ignores the +/- V in the symbol since it
s
does not affect circuit behavior
4
Open Loop Behavior
v
o
V
s
+V
s
v
+
+
v
o
v v - v
- - + -
-V
s
-V
s
v = A(v - v )
o + -
5
Comparator Circuit
v
o
+V V
s
v s
+
+
v V
o
v
in v
- -
-V
v
s
in
-V
s
 V if v > 0
s in
V = −
o
− V if v < 0

s in
6
Example
v
o
V
s
v +V
+ s
Csin(ωt)
+
v
o
v v - v
- - + -
-V
s -V
s
7
Ideal Op Amp Behavior
+V
v s i v
+
+ +
+
Av v v
v in Ro o o
in
v i v
- Ri - - -
-V
s
i = i = 0
+ -
v - v = 0
+ -
8
Buffer Circuit
v
v in +
in + v
v o
o
-
-
v = v
in o
9
Summary
 Op amps are active devices that can be used to filter or
amplify signals linearly
 Ideal op amps:
i v
+ +
+
v i = i = 0
o
+ -
i v
- - - v - v = 0
+ -
 Circuits: comparator and buffer
10