Here, ??n is an electron mobility, ??p is a hole mobility, Cox is a capacitance of a gate oxide film per unit area, Weffn is an effective channel width of the nMOS transistor, Weffp is an effective channel width of the pMOS transistor, Leffn is an effective channel length of the nMOS transistor, and Leffp is an effective channel length of the pMOS transistor.