Harmonic distortion in the junction field-effect transistor with field-dependent mobility

It has been found that a harmonic analysis of the usual power-law transfer characteristic of the JFET does not yield equations which accurately predict the third-harmonic distortion products for short-gate structures. However, if field-dependent mobility in the drain-source channel is taken into consideration in the equations for the drain current, a transfer characteristic is obtained of the form , where ZDis the normalized channel height and Γ is the field factor. Equations for the distortion products M2and M3, which are derived from this type of characteristic, accurately predict M2and M3for actual devices as a function of physical parameters. Lower limits on the values of M2and M3which can be achieved in a practical JFET are presented.