Download ECE311 Lab 3 Setup

ECE311 Lab 3 Setup
1) Setup the DC power supply for +/- 15V tracking.
Use the DMM to verify the rail voltages then switch
off the output voltage.
2
LM3481
1
3
14
2
13
3
4
5
LM348N
1
6
LM3482
7
LM3483
8
LM3484
14
5
12
11
9
10
6
9
7
8
10
13
12
2) Select resistors found in the preliminary and
measure/record their resistance. Additionally, select
2 additional equal resistors for the inverting
amplifier (RA,B) shown in Figure 1. The inverting
amplifier is used to generate a difference signal by
inverting a 500mV, 1kHz sinusoidal signal taken
from the function generator. NOTE: You want R1 =
R2, R3 = R4, and RA = RB (As close as possible).
The 2 x R1 and R2 values shown in Figure 2 on
Page 2 are selected such that the gain of the noninverting amplifiers are as close to 10 as possible.
Select, measure, and record all resistance values
prior to building in this step. Next, calculate and
record the expected gains for the difference and
instrumentation amplifiers from the measured
resistance values. Calculate the %Error using the
ideal expected gain as the basis (i.e. the expected
gain of the difference amp is 1 while the calculated
gain based on resistance values is X).
3) Build the circuit as shown in Figure 1 on this
page. Apply a 500mV sinusoid at 1kHz to the circuit
from the function generator. Measure the RMS
input voltage to the difference amplifier at vi1 and vi2
and the RMS output voltage from the difference
amplifier using the DMM. Calculate the amplifiers
gain G and the %Error with respect to the ideal
expected value and the resistance calculated
values. G = vo / (vi2 – vi1) vi1 is inverted by 180º.
Use 2 LM348s to build. Setup the Inverting amp and the
difference amp on the first LM348N.
RB
R2
RA
R1
LM3483
vi1
R3
vsig
LM3484
vi2
R4
Figure1
HINT:
Labeling nodes with package pin numbers on the
schematic assists in troubleshooting!
+
vo
-
ECE311 Lab 3 Setup
4) Turn the output of the DC Power supply off.
5) Build the two non-inverting amplifiers on the 2nd
LM348N.
A) Move the output of the inverting amp on the first
LM348N to the vi1 non-inverting amplifier’s input.
B) Re-route the function generator’s output signal
from the input of the difference amplifier on the first
LM348N to the vi2 non-inverting amplifier input on
the second LM348N.
C) Route the outputs of the non-inverting amplifiers
on the second LM348N to the inputs of the
difference amplifier on the first LM348N as shown
in Figure 2.
D) Verify all connections and apply the DC bias by
turning the power supply outputs on.
6) Measure and record the RMS output voltage with
a 500mV peak-to-peak 1kHz. sinusoid applied.
7) Calculate the instrumentation amplifiers gain G
as VoRMS / ViRMS. Calculate the %Error with respect
to the calculate gain based on resistance
measurements and the %Error with respect to the
ideal gain derived in the lab preliminary.
8) You are done. Power off all equipment and tidy
the workstation. Have a good one.
RB
RA
LM3483
NOTE:
In Figure 1, the R1 and R2 resistors
are now named R3 and R4 on the
difference amplifier. Since R1=R3 and
R2=R4 in Figure 1 for a difference amp
with a gain G = 1 V/V then renaming
these resistors is not a problem. The 2
x R1 and R2 values in Figure 2 are
chosen such the the gain G of the noninverting amplifiers is 10 V/V.
LM3481
R4
R3
2 x R1
R2
vi1
R2
R3
vsig
vi2
R4
LM3482
LM3484
+
vo
-
Figure2