Operational Amplifier
Wei Lin
Department of Biomedical Engineering
Stony Brook University
Instructor’s Portion
Summary
This experiment requires the students to build an inverting amplifier and a
non-inverting amplifier using operational amplifier. The students will
estimate the gain of the amplifier and use ELVIS work station to measure
the real gain of the amplifier.
Uses
This lecture applies to all courses of virtual instrumentation.
Equipment List

Computers

NI-ELVIS benchtop workstation

Textbook: Medical Instrumentation
References
Student’s Portion
Introduction
The students will build the amplifiers based on the schematics diagram in
textbook. They will use the rules of ideal operational amplifier to estimate the
gain of the built amplifier. They are also required to develop a protocol to
measure the gain using the signal generator and oscilloscope in ELVIS
workstation.
Objectives

Building inverting and non-inverting amplifier
1
Theory
The inverting and non-inverting amplifiers are the basic amplifiers. The gain
of the amplifier is determined by the resistor network based on the rules of
ideal operational amplifier. Detailed descript can be found in the textbook
“Medical Instrumentation, Application and Design”. The schematics designs
are in the appendix.
Lab Procedure
1. Keep ELVIS workstation power off.
2. Identify the pin assignment of the operational amplifier LF353M.
(Figure 1)
3. Get familiar with the layout of breadboard. (Figure 2)
The following steps 4-12 are shown in figure 3 for inverting amplifier.
You may cut the leads of the resistors and adjust the wire length to
keep the components and wires lay flat on the board.
4. Place one LF353 on the breadboard.
5. Place the resistors on the breadboard and connect the pins of the
operational amplifiers using these resistors if possible.
6. Create lines of power supplies (+15V, -15V) and ground.
7. Connect the +15V to pin 8 of the LF353s (Vcc) and -15V to pin 4 of
both LF353 (Vee).
8. Connect the ground of the circuit.
9. Connect one input terminal to the FUNC OUT terminal.
10. Connect the FUNC OUT terminal to CHA+ of the oscilloscope and the
output signal to CHB+
11. Connect CHA- and CHB- to ground.
12. Verify that all the connections are correct.
13. Turn on the ELVIS workstation.
14. Launch ELVIS. Select oscilloscope and function generator. For
function generator, select frequency range as 0-50Hz, frequency as
20Hz, sine wave and amplitude as 0.1V. For oscilloscope, enable both
channels and adjust the channel A gain as 100mV and the channel B
gain as 5V. Enable the measurement feature for both channels by
clicking the MEAS buttons.
15. Measure the gain of the amplifier by comparing the amplitude of the
input and output signal. CHA is input signal and CHB is output signal.
Repeat steps 4 to 15 for non-inversing amplifier. However, the only
changes are the connection of R1 and input signal shown on figure 4.
Lab Report

Project objective

Measurement of amplifier gain
2

Compare estimated gain with measured gain.
Due on 10/9/2009
Figures:
1. Schematics Drawings: LF353, Non-inverting and inverting amplifiers. We will use OP A in
the chip.
3
Figure 2: The color lines indicate the connections of the holes on the board. For example, the
green lines show the holes are connected in the columns. The red and blue lines show the holes
are connected in rows and they are for the power and ground lines.
Figure 3. Prototype board layout for the inverting amplifier.
4
Figure 4. Changes from the inverting amplifier to non-inverting amplifier. 1. Connect R1 to the
ground. 2. Remove the wire connecting pin 3 of the OP amp to the ground. 3. Connect pin 3 of
the OP amp to FUNC OUT signal.
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Appendix:
1. Inversing amplifier:
V1
15 V
U1A
8
3
Input
1
R1
Output
V2
15 V
2
1kΩ
4
LF353M
R2
26.7kΩ
2. Non-inversing amplifier:
Input
V1
15 V
U1A
8
3
1
2
4
LF353M
R1
R2
1kΩ
26.7kΩ
Output
V2
15 V
6