We report the design, fabrication and excellent linear power performance at mm-wave frequency range of a modified InGaAs channel pseudomorphic MODFET structure. This structure replaced the conventional n + AlGaAs carrier supply layer by n + GaAs carrier supply layer. g., was improved at high gate bias due to the superior carrier transport property of n + GaAs compared to that of n + AlGaAs.This g., improvement results in relatively flat and broad fT and f.. .x versus gate bias curves.Consequently, record high P ldB of 0.68 W Imm with G'dB of 12.9 dB and power-added efficiency of 45% were achieved at 25 GHz on a 0.33 x 120 /lm2 device.This linear power performance, to our knowledge, is the best reported in the literature for mm-wave InGaAs pseudomorphic MODFETs of this gate length. The Pout at maximum-power-added-efficiency point was as high as 0.81 W Imm with 10.9 dB gain and power added-efficiency of 59%.
During elevated-temperature bias stress, InGaP/GaAs HBTs grown by MOCVD show a medium-term degradation in current gain of about 20% with an activation energy of 0.7 eV. They also show a corresponding decrease in base resistance and an increase in turn-on voltage. InGaP/GaAs HBTs grown by GSMBE, however, do not show this degradation. SIMS measurements show a five times greater hydrogen concentration of about 1019 cm-3 in the base layer of the MOCVDgrown epi as compared with the GSMBE epi. The degradation can be explained in terms of acceptor depassivation due to hydrogen out-diffusion from the epi during stress.
Over the past several years, analog hardware description languages (AAHDLs) have gained increasing acceptance in the areas of analog and RF circuit simulation. The widespread adoption of these standardized languages promises to bring substantial benefits to analog model developers and to the users of analog simulation tools. In this paper, we examine the applicability of the Verilog-A hardware description language for analog RF modeling tasks, with an emphasis on issues of importance to circuit designers, device modeling specialists, and simulation too1 developers. The current capabilities and limitations, as well as future directions, are discussed, Inndpx Terms -Hardware design languages, computer aided engineering, circuit simulation, semiconductor device modeling.
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