Filters mini-dissertation

After these January exams I'll be writing a small 5000 word mini-dissertation.

I'm currently thinking of "The effectiveness of negative feedback loops in brush-less induction motors" but I'd love to focus it on something to do with filters, but not sure what route to take.

Any suggestions?

Edit: I've also been interested in Sigma-Delta modulation. Do you think that'd be too advanced to learn fully and put into 5000 words?

bump.