try this one.(not flat but slide in your pad)
http://www.rei.com/product/695429
It's what I use. Often I only take this in the thick of summer.

Now if you are looking to drop some weight check out backpackinglight forums.
http://www.backpackinglight.com/cgi-...ums/index.html

They have guys on the site that make ultralight weight down quilts and places that sell them.

http://www.backpackinglight.com/cgi-...98&startat=120