ANALYTICALLY EXTRACTED ZTC POINT FOR GAAS-MESFET

Some current-voltage characteristics of GaAs MESFET at elevated temper atures have been measured and the existence of zero temperature coeffi cient (ZTC) points in the drain current of DFETs and EFETs are present ed. At these points of operation, with a specific value of gate bias, the device drain current characteristics are stable in temperature. Th e ZTC point for the saturation region of operation is presented for bo th types of devices, whereas for the linear region of operation the ZT C point is reached only with DFET. The existence of the ZTC point is s hown to depend critically on the flow of leakage currents. The ZTC poi nts are analysed with an analytical model that is capable of estimatin g the corresponding drain current and gate bias values. In addition, a n analytical model for the threshold voltage and transconductance para meter is discussed by starting from device physical and geometrical pa rameters for finding the ZTC point. The analytically solved results ar e shown to correspond closely to the experimental results.