Thanks for the suggestion. I have few more questions and I would be glad if you can help.
If I have few opamps and comparators that will have to be used for my open loop (say a summer, inv amp and a comparator), looks like I will have to provide a voltage reference for each and every circuit then.
What will I have to do if I use a comparator with a single supply, if I have to compare a sine wave from the output of the summer and a ramp signal.
Thanks again.