Explanation and quantitative model for the matching behaviour of poly-silicon resistors

We investigate the matching behaviour of poly-silicon resistors. Experimental results from an analog CMOS process with three poly-silicon options are discussed and compared with a quantitative model which is developed using fit parameter-free analytical calculations and Monte-Carlo simulations. It is found that mismatch is directly proportional to the grain size. A relation is derived that allows us to optimize devices for low mismatch circuit applications.