EE 525 – Electronic Circuits II Laboratory
6 OP-AMP Applications (I)
6.1
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6.2
Objective
Introduction to basic OP-AMP circuits.
Basic Description
The operational amplifier (henceforth referred to as “op-amp”) is a ubiquitous example
of a general-purpose analogue integrated circuit. When appropriately configured using simple
external passive circuit elements such as resistors and capacitors, it can be used to perform
operations such as addition, subtraction, differentiation, integration etc., on arbitrary analogue
input signals. Since it is an analogue device, its inputs and outputs must be treated as analogue
waveforms, though certain op-amp circuits can be built whose outputs (or inputs) can be
interpreted as digital signals (e.g. digital to analogue converters, or DAC’s). Figure 1 shows a
typical op-amp in an eight-pin dual inline package (DIP).
Figure 1: A 741 Operational Amplifier Package.
This figure shows the pin outs for the IC and the schematic (or black-box)
representation of the op-amp as a right-pointing triangle with five (or three if you don’t count
+/-VCC) terminals. The “Null Offset” pins are never shown in schematics; even the supplies
are often left out. We shall not be needing the null offset pins in this lab, which can be left
floating when not in use. “NC” stands for “no connection”. Pin 2 (v−) is known as an
+
inverting terminal, while pin 3 (v ) is called a non-inverting terminal.
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EE 525 – Electronic Circuits II Laboratory
Various complicated circuits can be constructed by OP-AMP. These circuits are
fundamentally composed of basic circuits. We will introduce a few basic circuits of OP-AMP
used as amplifiers.
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Inverting amplifier circuits
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Non-inverting amplifier circuits
Several simple application circuits are developed according to the above two circuits, as
indicated in the following list:
(1) Voltage follower (Buffer)
(2) Substracter
(3) Adder
(4) Clipper (Limiter)
(5) Constant voltage circuit
(6) Constant current circuit
(7) Differential circuit
(8) Integrator circuit
This week’s experiments only involve basic inverting, non-inverting amplifiers.
6.3
Experiment Equipments
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KL-21001 main experiment unit
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Breadboard
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Multimeter
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Oscilloscope
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Function Generator
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741 Opamp, Resistors
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EE 525 – Electronic Circuits II Laboratory
6.4
Procedures
Procedure 1 – Inverting Amplifier
1. Setup the circuit in Figure 1.
Figure 1
2. Adjust the signal generator to 1 Vp-p 1 kHz sine wave.
3. Using oscilloscope, observe the input and output waveforms. Record them in
Graph 1.
Graph 1
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EE 525 – Electronic Circuits II Laboratory
4. Comment on the amplification type
Amplification Type = _________
5. Calculate the theoretical gain:
Gain (AV)calculated = ________
6. Measure the practical gain:
Gain (AV)measured = ________
7. By increasing the input voltage amplitude, determine the maximum output
voltage deviation limits.
Voutput max = ______ ,
Voutput min= ________
8. Comment on these limits, is it possible to change these values?
Procedure 2 – Non-iverting Amplifier
1. Setup the circuit in Figure 2.
Figure 2
9. Using oscilloscope, observe the input and output waveforms. Record them in
Graph 2.
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EE 525 – Electronic Circuits II Laboratory
Graph 2
10. Comment on the amplification type
Amplification Type = _________
11. Calculate the theoretical gain:
Gain (AV)calculated = ________
12. Measure the practical gain:
Gain (AV)measured = ________
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