Abstruct-The modeling of low-frequency dispersive effects due to surface state densities, deep level traps and thermal phenomena plays an important role in the large-signal performance prediction of 111-V FET's. This paper describes an empirical modeling approach to accurately predict deviations between static and dynamic drain current characteristics caused by dispersive effects in 111-V devices operating at microwave frequencies. It is based on reasonable assumptions and can easily be embedded in nonlinear FET models to be used in Harmonic-Balance tools for circuit analysis and design. Experimental and simulated results, for HEMT's and GaAs MESFET's of different manufacturers, that confirm the validity of the new approach, are presented and discussed together with the characterization procedures required.
This paper presents the configuration of the Ka-band radiometer developed for the Phase II of the QUIJOTE radio astronomy experiment, as well as the design of the different subsystems involved in the instrument. The new configuration, consisting of around 30 modified receivers working in the 26-36 GHz band, avoids the need of a rotating polar modulator at cryogenic temperatures, which is a source of mechanical and thermal difficulties. Moreover, the larger number of receivers will increase the instrument sensitivity. These two aspects are a clear advantage over the receiver developed for the experiment Phase I. The present paper also gives detailed information of some designed subsystems such as the feedhorn, the polarizer, the orthomode transducer, the cryogenic low-noise amplifiers and the back-end module.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.