# PSPICE help

Discussion in 'Homework Help' started by Spoder, May 12, 2014.

1. ### Spoder Thread Starter New Member

May 12, 2014
6
0
Hi there everyone,
I'm currently busy trying to complete my seminar project and I ran into a bit of a problem. I'm quite new to the whole pspice related stuff and I'm avare that this problem might me fairly basic but I have no idea how to solve this.
So the task was to get the schematic of Cable Amplifier using OPA660 from Texas Instruments website and then "test the ability to transfer digital dual-state signals of 0V and 1V levels and experimetally determin the highest possible transmission rate(bit rate) of the processed data." I'm quite sure that i have to basically change the imput source to 0-1V pulse, but the exact form somehow escapes me. The output should be a graph where the square wave gradually deforms but I just don't get how to achieve it exactly. So if anybody knows how to solve this please let me know, any help will be hugely apreciated and do not hesitate to ask for any further information to help you understand my problem assuming I didn't express everything clearly enough.
Thanks Mark

2. ### MrChips Moderator

Oct 2, 2009
14,514
4,279
Think of your goal: to determine the highest transmission rate.

Transmission rate is equivalent to frequency.

So your input signal is a square wave of a known frequency.

What happens when you increase the frequency of the square wave?

3. ### crutschow Expert

Mar 14, 2008
16,540
4,458
That type of test needs to done using the Transient Analysis function. Is that what you are using?

4. ### Spoder Thread Starter New Member

May 12, 2014
6
0
Yeah thats it, I'm ought to find the certain frequency when the square wave starts to degrade but everything I tried ended up showing me not degrating square wave. This is what my netlist looks like after I changed up my source and analysis type.

***
OPA660
*
R1 8 0 50
R2 8 3 150
Re 2 0 42
RL 5 0 150
Rq 4 1 250
V 8 0 AC 1 PULSE(0 1 0 0 0 2.5u 5u)
Vplus 7 0 5
Vminus 0 4 5
X1 1 2 3 4 5 0 7 5 OPA660X1
*
.lib OPA660X1.lib
.tran 1u 50u
.probe
.end

I think it should be solved using transient analysis but that just shows me time process.

5. ### JoeJester AAC Fanatic!

Apr 26, 2005
3,675
1,536
Is your transmission line model somewhat realistic?

6. ### Spoder Thread Starter New Member

May 12, 2014
6
0
It is, and the layout is supposed to be correct as well. The main problem might be that I'm not entirely sure what to put on Y axis of the graph.

7. ### crutschow Expert

Mar 14, 2008
16,540
4,458
You look at the input and output of the amp.

8. ### Spoder Thread Starter New Member

May 12, 2014
6
0
Meaning what exactly? Shall I use double Y axis and then print imput and output on it?

9. ### crutschow Expert

Mar 14, 2008
16,540
4,458
I'm not that familiar with Pspice, but yes, you plot the input and output (voltage probes) on the Y axis with time on the X axis. You don't need a double Y axis, you can print both on the same plot. What version of Pspice do you have?

10. ### Spoder Thread Starter New Member

May 12, 2014
6
0
The version I'm currently using is PSPICE AD Lite 16.6. Thanks for help I'll try that, but I think I already did that and didn't get exactly what I was looking for. the X axis should be frequency I think becouse I have to find certain frequency where the data is too deformed.

11. ### Spoder Thread Starter New Member

May 12, 2014
6
0
Still no progress, I'm getting kinda frustrated here.

Apr 26, 2005
3,675
1,536