The 22-year-old is currently enjoying a good season in the Bundesliga and his performances have been noticed by the Gunners.
Philipp made his debut for the Freiburg senior side in 2014 after making his way through the youth teams of a number of German clubs including Hertha Berlin, Tennis Borussia Berlin and Energie Cottbus.
His debut came against Stuttgart in a Bundesliga match in April of 2014 and he then established himself in the first team, going on to make 76 appearances for Freiburg, scoring 14 goals and providing 21 assists in all competitions.
This season, Philipp has been playing in a number 10 role behind the striker, and he has performed well in the Bundesliga with five goals in 13 league matches so far. Sports Bild valuation of the player is €4million or £3.5million.