A nonlinear method to estimate model parameters of junction field-effect transistors

This paper describes a method to estimate the model parameters of junction-type field-effect transistors. The characteristics of the device under test are expressed by a nonlinear equivalent circuit with a dependent current source. To estimate all unknown parameters to specify the characteristics of the device, a measurement circuit is sequentially configured into three independent modes by a desk-top microcomputer. Raw data acquired in each measurement mode are sent to another computer to obtain a nonlinear estimation of the model parameters concurrently with data acquisition. The curves characterized by the estimated parameters are found to fit well to the original data. A newly designed jig for measurement (including relays to change the circuit mode) is developed utilizing the IEEE standard 488-bus system. In cooperation with additional measuring instruments, fully automated acquisition and estimation are made possible. Since estimated values of the parameters are stored by the multiuser, host computer with a device name, they are ready to be used for such a general purpose circuit simulation program as SPICE 2.