Accurate modeling of drain current derivatives of MESFET/HEMT devices for intermodulation analysis

An alternative technique for modeling MESFET's for calculation of intermodulation responses is presented. This algorithm not only characterizes the IN characteristics of the device, but also the derivatives are accurately modeled. The method proposed utilizes a feed-forward neural network using the back-propagation method with the Levenberg-Marquardt (LM) algorithm. The advantage of this technique is that it can be used for both MESFET and HEMT devices. Furthermore, the need to extract fitting parameters is not required. This approach is truly independent of device process and technology, and can therefore be applicable to FET devices from SiC, GaN, GaAs and InP. Excellent agreement is observed between the neural network model and measured IN data and IN derivatives up to the 8(th) order. The I/V derivative evaluation was performed in Agilent's Advance Design Systems.