Preheat the oven to 350 degrees F. Grease and flour a 10-inch tube or bundt pan (or use baking spray).
PREPARE THE CAKE BATTER:
In a large bowl, use an electric mixer to combine the sugar and butter. Add the eggs and vanilla and beat well. In a separate bowl, whisk together the flour, baking powder, baking soda and salt. Add to the wet ingredients a little at a time, alternating with addition of sour cream. Beat well after each addition.
PREPARE THE FILLING:
In a small bowl, combine the brown sugar, flour and cinnamon.
ASSEMBLE THE CAKE:
Spoon a third of the batter into the prepared pan. Sprinkle half of the filling on top of the batter in the pan. Sprinkle half of the berries on top of that. Add another 1/3 of the batter- spread to cover the berries. Then sprinkle the rest of the filling, then the rest of the berries, then top with the remaining batter.
Bake for 55 to 65 minutes, or until a toothpick inserted near the center comes out clean. Cool for about 20 minutes, then turn the cake out onto a rack to cool completely. If you are serving this next day, wrap well with plastic wrap. It's great the next day!