Home > Community > Forums > PCB Design > Problems with parametric analysis in pspice

## Email

Recipients email * (separate multiple addresses with commas)

Message *

 Send yourself a copy

## Subscribe

Intro copy of the newsletter section here, some intro copy of the newsletter. Instruction of how to subscribe to this newsletter.

First Name *

Last Name *

Email *

Company / Institution *

 Send Yourself A Copy

# Problems with parametric analysis in pspice

Last post Fri, Mar 29 2013 7:18 AM by oldmouldy. 5 replies.
 Started by madhuraj 26 Mar 2013 12:13 PM. Topic has 5 replies and 790 views
• #### Tue, Mar 26 2013 12:13 PM

• Joined on Thu, Feb 14 2013
• bangalore, Karnataka
• Posts 16
• Points 230
Problems with parametric analysis in pspice
 Hi,I was trying to do a parametric analysis with AC Sweep. I was sweeping a particular resistance value from 400 ohms to 1100 ohms in steps. Actually the bode plot (DB and phase) at some particular point in the circuit should  show a sharp turnaround at around 520 ohms. This was proved when I was changing the values manually and performing the AC sweep. But when I performed a parametric sweep this change was not seen , the curves were following same trend as in case of 400 ohms but with some minor offset in each case, but in actual case if you look at the curves when it is at 1100 ohms and when it is at 400 ohms there should be a huge differenece. I am not sure why this is happening. Has anyone faced similar problem ? please help meOne more point is if I want to sweep to different parameters at a time, is there any other way other than using IF statement,Best regardsMadhuraj
• Post Points: 20
• #### Thu, Mar 28 2013 1:29 AM

• alokt
• Joined on Fri, Aug 22 2008
• Posts 232
• Points 3,335
Re: Problems with parametric analysis in pspice
 Can you share the circuit or just .out file? It's difficult to comprehend the problem and potential reason for same, base don above details.
• Post Points: 20
• #### Thu, Mar 28 2013 5:07 AM

• Joined on Thu, Feb 14 2013
• bangalore, Karnataka
• Posts 16
• Points 230
Re: Problems with parametric analysis in pspice
 Hi I am attaching the output file when I was performing a sweep of resistence values from 440ohms to 1100 ohms. I am also providing a snapshot below, It shows the output when the resisteance was 440 and when the resistance was at 600 ohms. If you look at Node 2, Node 11 you can see the Voltage values are 5.7522   and 1.2223 respectively when the resistance is 400 ohms. And  the respective values are 5.7713 and   1.4955 when the resistance is 600 ohms, I mean there is not much difference, but when I am not doing a sweep I am only checking a contant resistance the values are not maching . For example if keep resistance as 600 ohms and run the simulation, the above mentioned values were, .0071 and .0018 respectively (Please see the snap shot in Bold for this). Also there are problems with other points also, I am only mentioning these two for example. The point 11 is the output of a particular op amp I developed on basic op ampmodel 741 available in pspice. I am not sure will there be any issue with this model, but I had checked model response independently and it was matching with the data sheet results. Please let me know if you can get some clues from this. Once again thank you for your help, regards Madhuraj
• Post Points: 20
• #### Thu, Mar 28 2013 5:27 AM

• alokt
• Joined on Fri, Aug 22 2008
• Posts 232
• Points 3,335
Re: Problems with parametric analysis in pspice
 I would require complete out file, mainly the portion where circuit connectivity and simulation parameters are defined. I would run the same circuit at my end. I hope those are not confidential and can be shared. If that is confidential, you may want to create and share  small circuit to recreate the problem.
• Post Points: 20
• #### Thu, Mar 28 2013 6:02 AM

• Joined on Thu, Feb 14 2013
• bangalore, Karnataka
• Posts 16
• Points 230
Re: Problems with parametric analysis in pspice
 Hi,The output file was already attached in the end as a text file,thanksMadhuraj
• Post Points: 20
• #### Fri, Mar 29 2013 7:18 AM

• oldmouldy
• Joined on Tue, Jul 15 2008
• Woking, Surrey
• Posts 1,265
• Points 21,605
Re: Problems with parametric analysis in pspice
 Select the DSN file in Capture, Project Manager window, then File>Archive project, don't set the Add Libraries but do add this file  -saacl_updated.lib  - an additional file, create a single archive file and attach it to the forum. That will allow others to investigate the simulation with your settings.
• Post Points: 5