An efficient small signal parameters estimation technique for submicron GaAs MESFET´s

In this investigation, a software tool has been developed which computes AC behavior of mm-wavelength GaAs metal semiconductor field effect transistors (MESFETs) by using observed DC characteristics. The DC characteristics of a MESFFET are first simulated by using the fabrication parameters of the device which are then compared with the observed response. Once a good match is attained by minimizing RMS error values, the device AC parameters are then evaluated by employing the observed DC data. The technique ensures that there should be no discrepancy in the device small signal parameters caused by either the interfacial layer at the Schottky barrier or the short channel effects which are normally there in submicron devices. The validity of the developed technique is demonstrated by comparing the estimated values of intrinsic small signal parameters of a MESFET with the observed ones. For this purpose, the intrinsic small signal parameters values have been calculated from the observed S-parameters of the device by using a de-embedding technique. It has been shown that an accurate DC modeling is a key to predict an accurate AC small signal equivalent circuit of a device. Furthermore, the developed technique is highly time efficient because it uses DC measurements for the estimation of AC parameters of a GaAs MESFET.