Speaking to Esquire magazine, the 27-year-old actor likened the role to playing Hamlet.
"I tried to make it as funny as it should be but it's a bit like playing Hamlet," he said. "It has to be your version. The Doctor is so committed, whoever plays him.
"So I tried to be creative and artistic, and silly, and crazy, and also the cleverest man in the world, and part of that is there's a rapidity to the way he speaks."
He added: "He's an intergalactic genius, a superhero-ish, mad, fumbling, bumbling, science geek. He's everything you can pluck from any universe and put into him."
> Moffat: Matt Smith like a drunk giraffe