Transient performance of four-terminal field-effect transistors

This paper extends previous work on the low-frequency operation of four-terminal field-effect transistors (FTFET´s) by developing a model for the transient as well as the low-frequency performance of a symmetrical device, operating in the region beyond pinch-off. The model, which represents the FTFET in any of its possible modes of operation, is derived systematically from consideration of the physical makeup of the device. As a consequence, the element values are determined as explicit functions of the physical makeup and the bias voltages at the two gates; alternatively, they can be determined from a set of terminal measurements. In addition, in conjunction with the development of the model, expressions are derived for the functional dependence on gate biases of the gate-source capacitances present in any of the various modes of operation. Experimental results for the step-function response of the device are in good agreement with theory for broad ranges of source and load terminations. Good correlation has also been obtained for the functional dependence of the gate-source capacitances.