Lab 1 Review of Basic RC circuits - EE 420L
Authored
by Jeremy Garrod
01/25/2017
garrod@unlv.nevada.edu
Pre-lab work
1) request CMOSedu account
2) review entire write up
3) review material on editing webpages
Lab work
For
this first lab simulate, and verify the simulation results with
experimental measurements, the circuits seen in Figs. 1.21, 1.22, and
1.24 (use a 1 uF cap in place of the 1 pF cap) of the book.
Your results should be similar to, but more complete than, the
simulation results seen on pages 17 - 23. In your report, and for
each circuit, show the- Circuit schematic showing values and simulation parameters (snip the image from LTspice).
- Hand calculations to detail the circuit's operation.
- Simulation results using LTspice verifying hand calculations.
- Scope waverforms verifying simulation results and hand calculations.
- Comments on any differences or further potential testing that may be useful (don't just give the results, discuss them).
Experiment 1:
Figure 1.21
SPICE Transient
analysis
SPICE AC analysis
hand calculations
Scope
output
| Figure 1.21 | Simulation | Experimental | Theoretical |
| Magnitude (mV) | 621.5 | 560 | 622.7 |
| Time delay (S) | 700u | 726u | 715u |
| Phase (Degrees) | -51.4881 | -57.93 | -51.45 |
The
above table summarizes up the key information from the experiment
pictured. The experimental values that were obtained were very close to
both the theoretical and simulation values. The slight variation could
have been caused by many factors such as the capacitor not being
exactly 1uF along with human error.
Experiment 2:
Figure 1.22
SPICE transient
analysis
SPICE AC analysis
Hand calculations
Scope output for timd delay
Scope output for amplitude
| Figure 1.22 | Simulation | Experimental | Theoretical |
| Magnitude (mV) | 703 | 740 | 694 |
| Time delay (S) | 93.3u | 96u | 95u |
| Phase (Degrees) | -6.84 | -6.912 | -6.84 |
The
experimental values are all very close to the simulated and theoretical
values. A 2.2uF capacitor was used instead of a 2uF capacitor, which
could be one of the reasons that the magnitude of Vout is a bit
different. Other factors that lead to different experimental values are
human error as well as the resolution of the oscilloscope that was
used. It would only measure in 20mV increments, so the measured
magnitude is just an approximation.
Experiment 3:
Figure 1.24
Rise Time simulation
Delay Time simulation
Hand calculations
Scope output
| Figure 1.24 | Simulation | Experimental | Theoretical |
| Rise Time (S) | 1.83m
| N/A | 2.2m |
| Delay Time (S) | 859u
| N/A | 700u |
There
were quite a few issues with this experiment. First, I was not able to
tell exactly where to put the cursors in my simulation, so I ended up
using an educated guess. That proved to be quite inaccurate. Another
iss was with the phsyical experiment itself. I was only able to get a
trianlge wave as the output at the time of the experiment. I came to
the conclusion that my frequency was too high due to the fact that the
pF capacitor was changed to a uF capacitor. By the time I figured it
out, the lab was closed and I was not able to redo the experiment.
Figure 1.23 Frequency Response Measurements:
In
order to gather the needed data, an oscilloscope was hooked up to the
circuit and the function generator was set to the different
frequencies. The phase and magnitude were read directly off of the
oscilloscope
| Frequency (Hz) | Phase (Degrees) | Magnitude (dB) |
| 20 | -11.5 | Could not measure |
| 100 | -34.56 | -1.31 |
| 200 | -49.9 | -3.87 |
| 1k | -75 | -15.92 |
| 10k | -83.9 | -33.98 |
| 25k | -86.7 | -41.94 |
Measured
| Frequency (Hz) | Phase (Degrees) | Magnitude (dB) |
| 20 | -7.16 | -0.0697
|
| 100 | -32.14 | -1.445 |
| 200 | -51.488 | -4.115 |
| 1k | -80.957 | -16.076 |
| 10k | -89.088 | -35.972 |
| 25k | -89.635 | -43.93 |
Simulated
Conclusion:
The
experiment yielded results that were very similar to those from the
simulations as well as theoretical values. The third experiment was the
only real issue there was,. The other difference could easily be
explained by human error in measuring along with imperfect components.
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