Download ECE4205: Advanced Circuit Design Final Exam Project Presentation and Questions Guide: Presentation:

ECE4205: Advanced Circuit Design
Final Exam
Project Presentation and Questions Guide:
Presentation:
For the presentation, I expect mostly figures of circuits and simulation results, along with your
conclusion on the parameter (e.g., I think IB = 20nA is the best value here). I may ask questions
about your test setup or your results. For example:
Testing parameter X:
The simulated circuit was:
Which gave results:
200
150
100
50
0
1.0Hz
10Hz
100Hz
... V(U1:OUT)
1.0KHz
10KHz
100KHz
... I(U1:-)
Frequency
1.0MHz
10MHz
100MHz
... V(U1:-)
Then you might say:
”To test this parameter, I thought that an integrator circuit would be best. I measured the voltage
at the output while I swept the resistance value. I found that the most consistent value was 175,
until the resistance value got too large. However, at that point, the test isn’t as reliable, so I
believe that 175 is the best result.”
To which I might ask:
“How does the value of the capacitor affect the circuit here? You chose a very large value,
why?”
You will find some of the PSpice op-amp model parameters to be exactly what you expect them
to be. Others, you may find to be a bit different than what you expected or the datasheet shows.
Yet others may not work, or may not be testable. Remember, your goal is to test the op-amp
model and evaluate how well the model works! So, if something doesn’t work, don’t fret, mark
it as inoperable and explain that in your presentation.
In general, try to use the simplest circuit possible to do your testing. The more variables,
resistances, etc., the more extensive your test will have to be. And again, the datasheets should
give you good guidance in general – some of them have test circuits right on them, and also
some of the parameters will have tested conditions (20mV step, 10k load) that you can easily
repeat.
Additional Questions:
Additional questions will be from the rest of the class, including the material I ‘reviewed’
Wednesday, and/or from the TI uA741 datasheet. The document I used Wed is posted on
Blackboard along with the final project. An example:
“If I wanted to build an amplifier for a stereo that only allows bass (low frequency) signals to
reach it, what circuit might I use, and how would I select components for it?”
To which you might reply:
“The KRC filter is a simple filtering circuit to use, and for audio circuits you want a smooth
passband, so a Butterworth approximation would be best. This is a low-pass filter application, so
choose a cutoff frequency, and then use the equations to calculate C and R values.”
Then I might ask:
“Will this op-amp (looking at datasheet) work based on its frequency response characteristics?”
And you would add:
“The GBP is 1MHz, which is much greater than 20kHz audio range. As long as a large gain is
not needed, this op-amp will work very well.”
Bonus Questions:
I would like to elaborate, but I can’t. That takes away the bonus nature! You should expect a bit
more in-depth types of questions, for example:
“What changes about an op-amp’s operation if the power supply is reduced from +/-15V down to
+/-5V?”
Grading:
Your project/presentation grade will be based on attaining values and explaining them for Part I,
and demonstration of results in Part II. Of course, if something isn’t quite right, I will ask a
question about it – if you are correct or you catch your mistake, you will get a minimal penalty.
Appointments:
Appointments will NOT all be in my office! They will be:
Tuesday, 9am – 11am: My office, Whitt 352
Tuesday, 11am – 3pm: Whitt 302 (main office, conference room G)
Tuesday, 3pm – 4pm: Whitt 651
Tuesday, 4pm – 9pm: Whitt 302 (main office, conference room G)
Wednesday, 9am – 3pm: Whitt 457
Wednesday, 3pm – 4pm: My office, Whitt 352
Wednesday, 4pm – 9pm: Whitt 457
Your time is limited to 25 minutes. That gives you 10-15 minutes at most to demonstrate your
results, so don’t make a 30 page presentation. If time runs out, I have to stop you, as the
appointments are booked solid back-to-back! Bonus questions will of course be last. I will be
strict about timing, so arrive a few minutes early! Remember I will give you your final project
grade before you leave!