Position a rack in middle of oven and preheat to 350°F. Butter a 9-inch springform pan and wrap outside with foil.
Make crust: Stir together crumbs and butter with a fork. Press mixture onto bottom of pan and bake until set, 8 to 10 minutes. Cool on a wire rack. Reduce temperature to 325°F.
Make filling: Blend sugar and ginger in a food processor until ground. Add pears and blend until smooth. In separate bowl, beat cream cheese until fluffy. Add sour cream and beat until smooth. Gradually add sugar mixture, scraping down sides of bowl, and beat until smooth. Beat in eggs one at a time, then beat in vanilla and salt.
Pour filling into springform pan, set in a roasting pan, place in oven and pour in enough boiling water to reach halfway up sides of pan. Bake for 75 to 80 minutes, until center is almost set but jiggles slightly. Remove from oven and let cool on wire rack in water bath for 15 minutes, then remove pan to rack to cool. Remove foil and refrigerate cheesecake, loosely covered, until chilled, at least 12 hours.
Remove pan sides, cut cake into wedges and serve.