op amp

Operational Amplifiers:
Basic Concepts
Prof. Greg Kovacs
Department of Electrical Engineering
Stanford University

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Design Note: The Design Process
• Definition of function - what you want.
• Block diagram - translate into circuit functions.
• First Design Review.
• Circuit design - the details of how functions are
accomplished.
– Component selection
– Schematic
– Simulation
– Prototyping of critical sections
• Second Design Review.
• Fabrication and Testing.
EE122, Stanford University, Prof. Greg Kovacs
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EE122 Parts Kit
EE122, Stanford University, Prof. Greg Kovacs
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Parts Kit Guide
LT1175
LT1011
Adjustable
Comparator
Negative
Voltage
AD654 V-F
Regulator
LT1167 Converter
Instrum.
Sockets
Amp
7805 +5V
Regulator
Yellow LEDs
MJE3055 NPN
Power Transistor
Bright Red LEDs
555 Timer
IRLZ34 Logic-Level Power
LM334 Temp. Sensor
MOSFET (N-Chan)
CdS Cell
LT1036 Voltage
Regulator +12/+5
SFH300-3B
LT1033 Voltage
Phototransistor
Regulator 3A Negative,
LT1056 Op-
LTC1064-2
Adjustable
Amps
Switched
Capacitor
Filter
EE122, Stanford University, Prof. Greg Kovacs
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Each set of five pins are shorted
together internally so you can
make multiple connections to one
i.c. pin or component lead...
Each of the long rows of pins is shorted
together so you can use them as power
supply and ground lines...
Protoboards...
EE122, Stanford University, Prof. Greg Kovacs
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USE decoupling capacitors (typically
0.1 µF) from each power supply rail to
ground. This is essential to prevent
unwanted oscillations.
The capacitors locally source and sink
currents from the supply rails of the
chips, preventing them from “talking”
to each other and their own inputs!
EE122, Stanford University, Prof. Greg Kovacs
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Point-To-Point Soldering
On A Ground-Planed Board
EE122, Stanford University, Prof. Greg Kovacs
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What Is an Op-Amp Anyway?
OBJECTIVES (Why am I sitting in this classroom?)
• To obtain a practical understanding of what operational
amplifiers (“op-amps”) are and some applications they
can be used for.
• To understand the basic op-amp circuit configurations.
• To understand the basic characteristics (good and bad)
of op-amps before measuring some of them in the lab.
• To keep your parents happy!
"We don't need no education...."
We don't need no education....
EE122, Stanford University, Prof. Greg Kovacs
8

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The Ideal Op-Amp
1) The input impedance is
infinite - i.e. no current ever
V1
flows into either input of the
op-amp.
A(V2-V1)
+
2) The output impedance is
V2
-
zero - i.e. the op-amp can
drive any load impedance to
any voltage.
3) The open-loop gain (A) is
infinte.
The Op-Amp produces an output
voltage that is the difference between
4) The bandwidth is infinite.
the two input terminals, multiplied by
the gain A...
5) The output voltage is zero
when the input voltage
difference is zero.
EE122, Stanford University, Prof. Greg Kovacs
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Types of Op-Amps
• Low power
• Single
• Low noise
• Dual
• Low offset
• Quad
• High power
• High voltage
• High speed
NICE
HAT!
Traditional costumes of
analog circuit designers.
EE122, Stanford University, Prof. Greg Kovacs
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