The Integral Function Method: A New Method to Determine the Non-linear Harmonic Distortion

The analysis of harmonic distortion is of prime importance for analog and mixed integrated circuits, where MOSFET transistors can be used either as linear resistor in mixers and filters or in the saturation regime in transconductance amplifiers. The determination of the nonlinear harmonic distortion is normally done analytically by the Fourier Methods. Recently we presented a completely new method. which we called Integral Function Method (IFM) that allows the analysis of the harmonic distortion through the calculation of THD, HD2 and HD3. IFM requires the knowledge of the DC transfer characteristic of the device or circuit under study. The IFM combines simplicity and computer efficiency with accuracy. In this work we resume the basic definitions and expressions used by IFM for the harmonic analysis, and present its possibilities when applied to the following types of DC input-output transfer characteristics: long channel SOI MOSFET as linear resistor; short channel SOI MOSFET in the saturation region; short channel SOI MOSFET in saturation at high frequencies; voltage amplifier and differential amplifier. The behavior of these characteristics covers a very wide application spectrum. In all cases results obtained by IFM are compared with results obtained using the calculation of the Fourier coefficients (FC), AC measurements or by FFT in simulation.