This paper analyzes the effects of public R&D funding on R&D expenditure and patenting behavior of German firms. The main focus is the direct impact of subsidies on R&D and the indirect effect on innovation output measured by patent applications. We distinguish the productivity of purely privately financed R&D and additional R&D induced by public incentive schemes. For this, a treatment effects analysis is conducted in a first step. The results are implemented into the estimation of a patent production function. It turns out that both purely privately financed R&D and publicly induced R&D show a positive productivity.