Where does Donatello get his personality from the 90s films?
 

I noticed that Donatello in the first, second, and third films had way more of a laid back and humorous attitude, while still retaining some of his "geek" attributes, such as calling Casey claustrophobic and then laughing at him, or when he told Raphael that he was blushing and turning red, which I thought were pretty funny scenes. Has this personality been seen in the Mirage comics prior to the movies, because I haven't seen Donatello act like that in any other medium.

I'd say they more or less developed their own for the film(s). Don in Mirage is sort of a loner, so I'd not say they took any inspiration from there as far as his personality is concerned.