GENERAL THEORY FOR PINCHED OPERATION OF JUNCTION-GATE FET

A device oriented model is developed to describe the operation of the junction-gate field-effect transistor (FET) beyond pinch-off. The model is derived on the basis of a generalized structure with an arbitrary channel doping profile. It provides a qualitative and quantitative description of the current conduction mechanism, and is applicable over the entire dynamic range of device operation. Current conduction mechanisms in the vicinity of the source and the drain are examined separately. It is shown that the saturation of carrier drift velocities at high electric fields results in formation of a drain space-charge region of finite length. An approximate solution of the two-dimensional Poisson's equation is developed to describe the potential distribution within this region. A significant result of the device model is the prediction of a finite drain resistance in pinched operation, which shows a strong dependence on the device operation point. © 1969.