We present a new method for calculating the total harmonic distortion (THID) and the third harmonic distortion (HD3) of the output current-voltage characteristics of a semiconductor device. The method is based on the calculation of two functions which we call D and D3 and are based on a specific integration of the DC current-voltage characteristic of the device. In this paper we demonstrate that function D can be correlated with the THD and function D3 with the HD3, so that they can be determined in a much simpler way, with no need to use derivatives, Fourier coefficients or fast Fourier transforms. The new method is applied to calculate the harmonic distortion of a silicon-on-insulator (Sol) fully depleted (FD) MOS transistor in the triode regime to be used as an active resistor at the input of an operational amplifier in a MOSFET-C filter configuration. It is also demonstrated that the transistor I-DS-V-DS characteristics used in these calculations can be obtained from either measurements, analytical models or numerical simulations. (C) 2002 Elsevier Science Ltd. All rights reserved.