Spice simulation(ISIS PROTEUS) - strange impulses on graph?

Go To Last Post
11 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi folks.

I have problem with my simulation is ISIS Proteus software.
Generally it works as I want but I get strange impulses when MOSFET keys switch from one state to another. I assume it is an impact of capacitance on OP-amps? Anyway I don`t need these impulses on graph as I want to present only an idea of the algorithm. Please could you tell me what options I should change in SPICE simulator to generate less precise graph.
Is somwhere a reference with detailed description of Spice simulation options?

Below I attach picture of this graph.

Thanks in advance

Ifryd

Attachment(s): 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

hi,

the relating schematics would be very helpful.


Beware of the bear

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Ifryd wrote:
I don`t need these impulses on graph
Then load the image into your favorite image editor and paint over them.

Stealing Proteus doesn't make you an engineer.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The (excellent) Pulsonix SPICE I use comes with this document which might help:

http://www.pulsonix.com/downloads/manuals/Pulsonix%20Spice%20Users%20Guide.pdf

Leon

Leon Heller G1HSM

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

This MAY be due to the relatively high gate-drain capacitance on FETs. A high dV/dT on the gate will appear as spikes on the collector. IF this is the source of the problem, then you can reduce the amplitude of the gate drive, you can slow its dV/dT or you can choose a smaller FET with lower Cgd. You could also add some drain capacitance.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thanks for replies :)
Yes in my circuit I switch capacitors. I used power Mosfets. They have small Ron but unfortunatelly huge capacitances. Thnaks Jim for comprehensive answer.

Adam

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

FranzFortney wrote:
Excellent Jim. Your comment surely helps. Is that you in your avatar? I am just curious? lol

< hidden message removed; Plons >

Either that or he has some very distinguished friends.

David.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Moderator: Please deleter the above three postings and ban the users TeddyNguyen, chiche, manola. The postings all contain hidden spam. The spam is hidden by using a color=#FFFFFF or color=#F4F5F7 tag.

< I did. Logged their IP address and names. Nard >

Stealing Proteus doesn't make you an engineer.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

That is me. Hardly "distinguished".

As a follow up, that graph is likely to be approximately what the real signal would be. To smooth things as you would prefer in the real world, add some small capacitance (maybe 100pf to 1000pf) to ground at the output. You would do the same in the real circuit.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

See moderators? You didn't react to the first three instances of hidden spam in this thread (TeddyNguyen, chiche, manola). Now you got a third (lindapret88). This is how spammers work. You let them get away with it, so they keep coming back.

Stealing Proteus doesn't make you an engineer.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Not so grumpy Arnold. I have to sleep from time to time. I am no robot.

Nard

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tricia, and Ulyana. You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips