I am looking for a simple compiler that compiles a simple language, I need it to write a paper about it and to learn how compilers work, I am not looking for a sophisticated thi
Depends on your view of simple. You could look at one of the variouse available BrainFuck compilers. That's an extremely simple language and the compilers are veery small. But I don't know how much this will tell you about how a "real" compiler works.
What about looking at a small C compiler? C isn't very compilcated and I think this will give you some insight in compiler construction.