need help about modeling

[tieuquaybk]

i need to simulate transient response in Orcad (as determination ,that's circuit's response while input signal is sign() function (Heaviside 's function ) but i dont know how to model the input signal . Can anyone help me!
thank alot

 

[sunking]

use a comparator

 

[lichengcao]

use the tool 'Pspice stimulus editor' embeded in the orcad

 

[tieuquaybk]

i'm using Pspice stimulus
but don't know how to model the input signal as Heaviside function .