The second seeded Broncos grabbed a first half lead and then played stout defense to beat the sixth ranked Cougars, 30-6.
Northgate is now 9-2 on the season. The Broncos play second seeded Rancho Cotate (11-0) next weekend in the Division II semi-finals. Rancho Cotate defeated Las Lomas High, 21-14, on Friday night.
Newark Memorial finishes its season at 9-3. They posted a 40-8 victory last week over American High in the first round of the playoffs.