Lab 1 - ECE 420L
Authored
by Silvestre Solano,
Email: Solanos3@unlv.nevada.edu
1-30-2015
For Lab 1,
we had to construct and measure the circuits shown in figures
1.22, 1.23 and 1.24 (the 1pF capacitor is replaced with a 1uF
capacitor) of the CMOS book. Also, we had to compare the measured
results with hand calculations and LTspice simulations. Please note
that pictures containing data will have important or relevant data
enclosed in a red box for easier identification.
1.21
For the first circuit shown in figure 1.21 the LTspice schematic, waveform, and measured parameters are shown below.
According
to the simulation results, the peak voltage for the Vout is shown to be
622.246 mV. The time delay measured from the peak of Vout to the peak
of the corresponding Vin is shown to be 705.467 uS. The actual
measurements for this circuit taken in lab are shown in the following
two pictures. The first one shows the Vout to be about 700 mV and the second
one shows the time delay to be about 620 uS.
Vout
Time Delay
As
for the hand calculations, they show a peak voltage of 623 mV and a
time delay of about 715 uS. The hand calculations are shown below.
It
appears that there is some variation in the results for all three
methods. These variations are best shown in the table below. The
greatest variation is from the measurements made in Lab.
| 1.21 | LTspice | Hand Calculation | Measurement in Lab |
| Vout | 622.246 mV | 623 mV | 700 mV |
| Time Delay | 705.467 uS | 715 uS | 620 uS |
1.22
As before with the previous circuit, the LTspice simulation with schematic, waveform, and measurements are shown below.
The
LTspice simulation show to have peak voltage of about 693.19 mV for
Vout and a time delay of about 98.0592 uS. The actual measurements in
lab show a Vout of 800 mV and a time delay of 150 uS. The results are
shown below.
Vout
Time Delay
The
hand calculations seem to match the simulations. The Vout is calculated
to be about 694 mV and the time delay is about 95 uS. They are shown
below.
A table showing the results is shown below.
| 1.22 | LTspice | Hand Calculation | Measurement in Lab |
| Vout | 693.19 mV | 694 mV | 800 mV |
| Time Delay | 98.0592 uS | 95 uS | 150 uS |
1.24
For the circuit shown in figure 1.24, the LTspice simulation is shown below.
According
to the above simulation the time delay is shown to be 6.7 mS. However,
the 6 mS that are defined in the simulation parameters must be
subtracted from the 6.7 mS which results in the correct time delay of
0.7 mS The hand calculations are trivial and it is simply time
delay=0.7*R*C = 0.7mS
The actual measurements taken in lab seem to differ by 0.1 mS and the waveform captured in lab is shown below.
The table below shows the results.
| 1.24 | LTspice | Hand Calculation | Measurement in Lab |
| Time Delay | 0,70082 mS | 0.7 mS | 0.609 mS |
For
the circuits in figures 1.21, 1.22, and 1.24, the hand calculations and
the simulation results seem to closely match. However, the actual
measurements seem to differ significantly from the hand calculations
and simulations. This is probably due to the substandard equipment that
we are forced to work with and human error. For this particular lab,
the equipment used was probably the major issue due to the fact that we were
not assigned a breadboard before the experiment began and the lab seems to lack decent scope probes. Dr Baker told us
to "macgyver" the experiments without having taken the mandatory safety
lecture. If of course, we had an actual breadboard and functioning
oscilloscope probes, we might have gotten better results.
Apparently,
we have to make a table of arbitrary points on the frequency response
for for the circuit in figure 1.21. The LTspice results are shown below.
A table showing frequency, phase, and magnitude is shown below at has data points spaced at about 1dB magnitude.
| Frequency Hz | Magnitude dB | Phase Degrees |
| 82.18 | -1.03 | -27.31 |
| 124.5 | -2.07 | -38.03 |
| 160.5 | -3.05 | -45.24 |
| 197.6 | -4.05 | -51.15 |
| 237.7 | -5.09 | -56.19 |
| 279.3 | -6.11 | -60.32 |
| 320.8 | -7.04 | -63.61 |
To conclude this report, I will back up my stuff on my laptop/ flash drive/ email account / as shown below.
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