Hi folks!

I want to plot the THD vs. Frequency Response of an Amplifier Stage in Orcad Pspice!

Does anyone know how that runs?!

Thanks in Advance!

Best Regards
PowerAmp_

 

I am afraid, this is not possible.
The THD is a parameter that contans non-linearities of the device and, in contrast, the AC analysis (which is the only one showing the frequency on the horizontal axis) is a linear analysis.
I think, there is no way out than to determine the THD for different frequencies running different TRAN analyses.

 

Hi LvW!

Thanks for your statement!

I bought the book "Small Signal Audio Design" by Douglas Self and in the book there are plots of THD vs. Frequeny Response!

Maybe he is using another SPICE programm or uses other ways to plot them!

When I have found out how does it run i will post it here!

Best Regards

PowerAmp_

 

I think you need to analyse a real system. To get those numbers correct. What you can do is to run transient analysis to get an idea then clipping occurs. Clipping will affect the THD numbers in a drastic manner.

 

Looking in the book. I think most of the charts of that kind. Are made by eqipment from this vendor http://www.ap.com/products

 

Hi!

Probably he did it with some equipment like that!
Unfortunately I think there is no way to do that in Pspice!

Best Regards

PowerAmp_
http://dict.leo.org/ende/index_de.h...oc=0&resultOrder=basic&multiwordShowSingle=on

 

After some use of Google I found this
In TRAN setup you have to activate FOURIER and to specify the fundamental frequency of the signal you want to analyze as well as the corresponding node voltage. After completion of the analysis the result (THD in %) is written in the *.out-file.
I have not done these kind of analysis my self. The result from this analysis would probably not reflect the real world situation in a good manner. The analysis you want to do is THD+N(N=noise). And such type of analysis will only have a value then done on a real world system. But good luck with your project

 

Ok,
The THD in the output file is well-known by me.
Between real world and simulation is always a big difference!
I think I can continue my project without THD+N(%). ;-)

Best Regards
PowerAmp_