Hello Abid, I completely agree to your reply”It can be because of random seed thing. Well i suggest you to double click on every component you have used in your design especially the active components , you may see a simulation tab namely random , click on that and untick the generate seed option. It will definitely make your results stable.” This random generation of values is meant for inserting a noisy signal in lossy conditions. Switching the random generation off reals generates the required results.
Thanks for your kind suggestions.
Regards.