Cad-Oriented Models Of Packaged Low-Noise HEMTs From Measured Noise And Scattering Parameters

Abstract

CAD-oriented models of low-noise HEMTs have been obtained by an optimization technique that allows a close fitting of very accurate measurements of noise and scattering parameters performed on several samples. circuit model, in which the chip and package networks can not be separated. In this work a comparative model analysis is performed between two different series of packaged low-noise HEMTs to evidence the parameter-to-model correlations through a sensitivity analysis. For devices in the packaged form, the result of the extraction procedure is the overall I, Introduction Traditional modeling methods for low-noise HEMTs are based on scattering S parameter fitting only, since accurade noise N-parameter determination is timeconsuming and requires specialized measurement systems. employing one of the well-known noise models [1,2]. The complete charactlerization of several low-noise HEMTs in terms of both Nand S-parameters employing the measurement procedure reported in [3], allowed us the extraction of noisy small-signal models even for packaged devices. It has to be noted that in this case the parasitic elements are not determined by additional measurements and the packaged HEMT model is extracted as a whole equivalent circuit. Therefore, the element values also account for the chip-to-package interactions. As a consequence, different types of HEMTs having the same package can be characterized by different input/output configurations of the model. In this work a comp,wative analysis is presented between the circuit models of the packaged low-noise HEMTs of the NE32083A and the 2SK677 series by NEC and SONY, respectively. Usually the N-parameters are calculated from the extracted small-signal model by