In this paper, we proposed a new algorithm for stable numerical differentiation by optimizing node intervals. With the algorithm, noise-free differentiated values can be extracted within one-percent error. By overcoming noise problem due to numerical differentiation process, our algorithm can easily extract the differentiated Values. Also, it can be extended to high order differentiation. To confirm the proposed algorithm, we applied it to the analysis of MOSFET electrical characteristics. It will provide us with a useful analysis tool in the field of parameter extraction from numerical data such as device characterization. (C) 2009 Elsevier B.V. All rights reserved.