A new conventional mobility formula is advised to overcome the enigmas of the known formula. It is made possible to extract all device parameters including the series resistance for each device, and the formula is helpful in deriving an I-V formula over the entire linear region of MOSFETs. The proposed mobility formula is akin to the known one and can overcome the two problems inherent to the traditional mobility model of: (1) inability of explicitly assessing the series resistance, and (2) difficulty with analytical integration over the surface potential along the channel. The series resistance is extracted independently for each device, and its channel length dependence can now be discussed. A new formula is derived for the linear region where the role of important parameters is easy to interpret. It is discussed that the parameter n may differ with devices. When optimized, an average fitting error as small as approximate to 0.4% is achieved over the entire linear region. (c) 2007 Elsevier Ltd. All rights reserved.