# PSPice Lab Exercise - Differentiator (Circuit)

• Comp Sci
• Const@ntine
In summary, the person is trying to do some digital work on a project that they are not familiar with, and needs help.
Const@ntine
Homework Statement
This is a Lab Exercise, so it's more than one thing. The basic idea is that we need to "build" a Circuit and then examine the Waveforms through PSPice.
Relevant Equations
Uo = i*R = R*C*[(d*Uc)/(d*t)]
Us = Uc + Uo
Us >>> Uo
Look, this is a weird one, but I really need help. This is the Electronics Laboratory, that is supposed to be hands-on, but with Corona it got cancelled. However, they announced that we'd do it through the internet, had us download PSPice, and now we basically have to try and "translate" the exercise from the leaflets meant for a hands-on approach, to just doing it through this program.

Starting off, we're given this:

The "Us" reads "Frequency Generator". But inside the leaflet, it says that it's a "Source of Square Pulses".

The statement is:

"Draw this circuit in Spice for (α) R=5kΩ, C=2nF & (β) R=250kΩ, C=4nF "
So, we're dealing with two versions where we change the numbers. I get that. My problem is that I cannot find that particular Pulse Generator anywhere in the PSPice library. I also checked my leaflet, and can't find a single example where the circuit is left "open" at the sides (the Uo part). I checked the internet and the program's website, and I'm getting that the generator for square pulses is:

Then, the Exercise, says:

"Feed the circuit with Square Pulses of 4Vpp and frequency 0.5kHz."

In my leaflet, I basically have that Vpp is the full voltage between positive and negative peaks of the waveform; that is, the sum of the magnitude of the positive and negative peaks. I get that in the diagrams/waveforms. My question is, what does that mean for the values I'll asign to my "Us"?

Furthermore, as I have no other examples of such circuis, how am I suppose to create that in PSPice? I can do this (disregard the C and R values/names, this is just a quick example:

How am I supposed to add the "free ends" to the sides? Just add two more wires/buses? Then I suppose I should place the ground. However, as I'm not even sure if that's the correct Pulse Generator, I don't know how to proceed with the values I've been given.

The exercise continues with a second circuit, and I may update with more more info as we continue, but I really need help here just to start this. I know this isn't the exact way we're supposed to upload, but this is the first time I'm doing this, and have no previous experience with the program or how this whole thing works.

Hmm, that's a lot of words and I'm having a difficult time trying to understand your question. Is it: How to set up VPULSE to get square waves or what should you use?

I grabbed this from an old lab notes from the university I attended. I would bet my university got it from the cadence support site or maybe the's a help option somewhere. I don't have PSpice on my personal computer so I couldn't check, but I think the above would be sufficiently helpful, yes?

Thanks for taking the time to respond. Ultimately I gave up and sent the Professor an email to fail me, and I'll retake the Lab next year. I missed a few classes due to illnesses, and tried taking it without the proper knowledge, so when Corona hit and I couldn't have a "hands on approach" with the actual circuits at University, it became too hard. I called someone who teaches Electronics for some help, but he couldn't understand either, so I threw in the towel. Hey, better to retake it next year and be ready.

I was moving yesterday, which is why it took me too long to respond; apologies. And again, thanks for the taking the time to try this, I appreciate it!

OK, so we don't need to solve your problem until next year. But, a comment about using simulators, which you will want/have to do in the future.

They can be a real PIA to set up. There are a lot of test circuits that you'll have to do just to figure out how to get what you want. So, in this case of a pulse generator with confusing documentation, what I would do is make a circuit with just the generator and a resistor and make measurements to figure out how to get the wave form you want. It is usually less work than wondering if you read the documentation correctly.

Too many people put in a circuit and only measure the output. But then how do you know that you haven't made a mistake? The best way is to build your circuit up piece by piece, gaining confidence with each step that it is correct so far. Later you can skip some steps when you have used the particular simulator enough to be proficient.

Later on when you have a job doing this stuff without someone that has the answers, I think you will find that about 95% of the effort in using simulators is in verifying that you have correctly defined all of the models for your circuit.

Are you able to audit the class? I would go for it.

Tom.G

## What is a differentiator circuit in PSPice?

A differentiator circuit in PSPice is a type of electronic circuit that performs the mathematical operation of differentiation on an input signal. It is commonly used in signal processing and circuit analysis to find the rate of change of a signal over time.

## What components are typically used in a differentiator circuit?

The components used in a differentiator circuit typically include a capacitor, a resistor, and a voltage source. The capacitor and resistor are connected in series, and the input signal is applied across them. The output signal is taken across the resistor.

## How does a differentiator circuit work?

A differentiator circuit works by taking the derivative of the input signal with respect to time. This is achieved by the capacitor, which allows the input signal to pass through it, but blocks the DC component. As the input signal changes, the capacitor charges and discharges, producing a voltage across the resistor that is proportional to the rate of change of the input signal.

## What is the purpose of a differentiator circuit?

The main purpose of a differentiator circuit is to measure the rate of change of a signal. It is commonly used in applications such as audio and video processing, where it can be used to remove noise and improve signal quality. It is also used in circuit analysis to find the transfer function and frequency response of a circuit.

The advantages of a differentiator circuit include its simplicity, low cost, and ability to accurately measure the rate of change of a signal. However, it can be sensitive to noise and may produce high-frequency components in the output signal. It also requires careful design to avoid instability and oscillations.

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