Lab

Lab 1 - EE420L

Authored by Rodolfo Gutierrez

gutie284@unlv.nevada.edu

1/29/2016

Reviewing of basic RC circuits.

Experiment 1

Figure 1.21

Hand Calculations

Magnitude = 0.62267 Phase = -51.488 degrees Time Delay = 715 microseconds

Simulation for figure 1.21

The hand calculations and simulation results show that there is match for Vout's peak voltage and a match with the phase angle.

Simulated and measured waveforms for figure 1.21

When we compare the scope image with the spice simulation we see that there is a match in both phase and amplitude

As seen in the scope each square grid represents 1 volt for both channel inputs. CH1 displays Vin which peaks at 1 Volt and CH4 displays the Vout and it peaks at about 0.6 Volts. While the simulated image displays Vout's peak above 0.6 Volts the scope output was expected to be a tad bit lower due to the shortage of 1k ohm resistors. 1.1k resistors was used as a substitute which will cause our Vout's peak to be slightly lower.

Table 1.21

	Calculated	Simulated	Measured
Magnitude	0.62267 V	0.622677 V	0.6 V
Phase	-51.488 degrees	-51.4881 degrees	-57.6 degrees
Time Delay	715 microseconds	715 microseconds	800 microseconds

This table shows that there is a match between simulated and calculated values, however the measured results are different. The lower voltage was a result of using a 1.1k resistor, the different time delay was caused by poorly measuring the scope with the cursors. The scope image shows a 800 microsecond time display, which was used in calculating the phase angle.

Experiment 2

Figure 1.22

For experiment 2 we added in a 2 microfarad capacitor in parallel with our resistor.

Hand Calculations
ratio_1.22.jpg

Magnitude = 0.6935 Phase = -6.84 degrees Time Delay = 95 microseconds

Simulation for figure 1.22
SimulationPhase_1.22.PNG

Comparing the simulation and hand calculation shows that we should expect about 0.7 V as our outputs peak which a lagging phase of 6.84

Simulated and measured waveforms for figure 1.22

Since the phase angle is low our Vin and Vout waveforms are rather close to each other in phase. Our peak to peak measurment in time shows a time delay of 120 microseconds, meaning we are off the calculated and simulated time delay by about 25 microseconds. The Vout peak shown in channel 4 peaks at about 0.7V which nearly matches the calculated and simulated results.

Table 1.22

	Calculated	Simulated	Measured
Magnitude	0.6935 V	0.693516 V	0.7 V
Phase	-6.84 degrees	-6.84093 degrees	-8.64 degrees
Time Delay	95 microseconds	95 microseconds	120 microseconds

We have matched results for our simulated and calculated values. The measured peak voltage for Vout did match the expected values from both the simulated and calculated values. The time delay was once again a result of bad measurments from the cursors. Since the time delay measurment from the scope was used to calculate the measured phase shift, the phase result was off by about 2 degrees.

Experiment 3

Figure 1.24

For experiment 3 we are using the same circuit used in experiment 1, however we are using a square waveform instead of a sinewave

Hand Calculations

Simulated and measured waveforms for figure 1.24

The waveform shows that when Vin is 1 V the capacitor charges at the rate of 1-e^(-t/RC) and when Vin is equal to zero the capacitor discharges at the rate of e^(-t/RC). Both the simulated and measured waveforms shows that Vout reachs a peak slighlt above 0.9 V. The scope image shows that at about 1.4 ms the Vout voltage would have reached a voltage of 720mV while in our simulated waveform Vout reaches 0.7 volts at about 1.2 ms after Vin becomes 1 V.

Conclusion
Most of the data shown has been consistant with each other. With the only issues being the scope measurements, however the error caused by the measurments have been low and still shows that the data has been consistant with our expected results.

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