Objective: The purpose of this lab is to experimentally
construct and verify the frequency responses of two circuits. The
circuits to be studied are the passive RLC circuit shown in Figure
1 and the active network shown in Figure 2.
Pre-lab:
Determine the transfer function
Vo(jω)/Vi(jω) for the
circuits shown in Figures 1 and 2 below.
Plot the frequency responses (magnitude and phase using a
computer-based tool such as Matlab) for these circuits keeping in
mind:
linear and/or logarithmic axes may be used as may Decibels
(dB), so choose which will be easiest to replicate and verify
experimentally (i.e., you will be experimentally constructing
these same plots);
ensure key regions are readily visable for meaningful
comparison with experimental results; and
the frequency responses may be significantly affected by the
internal resistance of the function generator and/or impedance
of the oscillocope probe, so include their effects as
warranted.
Laboratory Procedure:
Frequency Response of an RLC Circuit
Construct the circuit shown in Figure 1.
Let vi(t) be a 2 Vp-p sine wave
for which you'll vary the frequency.
Use your prelab results as a guide as to what frequency range
should be used and experimentally find (via measurements) a
table of values for the frequency response (magnitude and phase)
of Vo(jω)/Vi(jω). Note
the function generator and oscilloscope display frequency in
Hertz and your plots are likely versus frequency in rad/sec, so
make sure to convert in whichever way you choose to keep the
units consistent. Take extra points in regions where the
magnitude or phase change quickly.
Compare your results with the calculated values plotted in the
prelab by recording the experimental data on top of the
calculated prelab data/plots.
How would one describe this circuit?
Does this passive circuit ever yield a gain larger than 1
(0dB)? If so, how is this possible?
Frequency Response of an Active Circuit
Construct the circuit shown in Figure 2.
Let vi(t) be a 2 Vp-p sine wave
for which you'll vary the frequency.
Use your prelab results as a guide as to what frequency range
should be used and experimentally find (via measurements) a
table of values for the frequency response (magnitude and phase)
of Vo(jω)/Vi(jω). Note
the function generator and oscilloscope display frequency in
Hertz and your plots are likely versus frequency in rad/sec, so
make sure to convert in whichever way you choose to keep the
units consistent. Take extra points in regions where the
magnitude or phase change quickly.
Compare your results with the calculated values plotted in the
prelab by recording the experimental data on top of the
calculated prelab data/plots.