Low-noise cryogenic X-band amplifier using wet-etched hydrogen passivated InP HEMT devices

Abstract
The performance of a cryogenically cooled -band amplifier for the geodetic VLBI -band (8.1-9.0 GHz) is pre- sented. The amplifier incorporates hydrogen passivated InP de- vices with 0.2 200 m gate. A comparison of the noise perfor- mance with selected commercially available GaAs high electron mobility transistor (HEMT) devices of similar dimensions is presented. The InP amplifier shows lower noise temperature ( = 4.8 K, = 0.07 dB) than GaAs, with very low power dissipation (2 mW per stage). This is the first report on the cryogenic noise performance of hydrogen passivated InP HEMT's in this frequency band.

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