Their reward for a seventh successive victory in this season's tournament is a return to stadium:mk next month and home nation advantage as they try to book safe passage to the final in Cardiff.
Saints were beaten 29-13 in France in the Pool stages last season, but bounced back to pick up a try-scoring bonus point in a decisive 34-0 victory at home.
"Watching Perpignan at the weekend it is easy to see they have threats all over the field. But we will go into the semi-final confident we have beaten them before and that we can do it again," said Mallinder.
"The more this team learns together in big games the better they will become. We are still inexperienced in terms of the Heineken Cup, but we've just won a quarter-final and moved on from last season.
"It was just about keeping going forward and testing them physically because we were confident we could play for the full 80 minutes. We were pleased to just be in it at half time. I'm just delighted with the team because I think we got stronger and stronger."
"To see your pack scrummage like that after 70 minutes and your defence to be hitting rucks and forcing turnovers is a great credit to the conditioning team."