ENGR337 Lab 2018
Lab 6 Instrumentation Amplifiers.
Due Feb 19, Monday 10 pm.
of this lab:
1. Be familiar with the Difference Amplifiers and Instrumentation Amplifiers.
2. Be able to design an Instrumentation Amplifier.
1. Measure the common-mode gain of the following difference amplifier.
Use Op Amp 741 cn
to build the following difference amplifier on your breadboard. Power
up your Op Amp using -10V and 10V; Inject a 0V offset, 100 mVp-p, 1 kHz
sinewave to the input as the common mode input. Report the result. You
should see almost 0 V AC output, but probably some DC output. Report
both the AC coupling and the DC coupling results.
Instead of using a sinewave, inject a DC voltage to the input. Try
these values: -2V, -1.5V, -1V, 0V, 1V, 1.5V, and 2V. Report the input
and output in a table.
Change the topology to the following, and inject a 0V offset, 100
mVp-p, 1 kHz sinewave to the input as the differential mode input
signal. Report the input and output.
Use the same circuit as above, use different resistances for R3 and R4
(R3=R4): 1k, 4.7k (you have done), 6.8k, 9.1k, 11k, and 20k. Report the
input and output sinewaves (Use AC coupling for this experiment).
Discuss the highest gain you can have for this topology.
Build the following instrumentation amplifier, Use R3=R4=4.7k,
R2=R1=1k; R5=R6=4.7k; Inject a common-mode DC voltage: -2V, -1.5V, -1V, 0V, 1V,
1.5V, and 2V, (use DC coupling) measure the output and report them in a table.
Design the resistance in the circuit above to explore the maximum gain
can be applied to this Instrumentation amplifier. The Op Amps are
powered up at -10V and 10V, the differential input (injected into VI1,
and ground VI2) is a 0V offset, 100 mVp-p, 1 kHz sinewave. The gain can
be easily modified from changing R1 for the first stage (but probably
do not use resistors <1k). You can use a fixed gain for the second
stage, say, 10k:1k, so you don't need to change it again.
Follow the lab
to avoid losing points.