In a 5- to 6-quart pan over medium-high heat, stir olive oil and garlic until garlic is limp but not browned, 2 to 3 minutes. Add lemon juice, wine, broth, and tomatoes.
Turn heat to high and stir often until sauce boils, about 2 minutes. Add pasta, return to a boil, then add shrimp. Stir often until pasta is tender to bite and shrimp are opaque but moist-looking in center of thickest part (cut to test), 5 to 8 minutes. Ladle into wide bowls and sprinkle with onions.