Quarter-micrometer low-noise pseudomorphic GaAs HEMTs with extremely low dependence of the noise figure on drain-source current

Quarter-micrometer pseudomorphic (PM) AlGaAs-InGaAs-GaAs HEMTs with an In mole fraction of 21% have been successfully developed, fabricated, and characterized. The devices are realized in a commercial technology by using a multiple-gate-finger layout with air bridges for the interconnection of the source pads and a Si/sub 3/N/sub 4/ passivation. PM HEMTs with a gate width of 6*20 mu m exhibit state-of-the-art noise figures of 0.65 and 0.82 dB with an associated gain of 14.5 and 11.5 dB at 12 and 18 GHz, respectively. The noise figure shows the lowest dependence on the drain-source current yet reported with Delta F/sub max/<0.12 dB for a wide biasing range from 25% I/sub dss/ up to 150% I/sub dss/ at 12 GHz when I/sub dss/=170-250 mA/mm.<
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