Effect of gate structures on noise characteristics of 0.15 mu m AlGaAs/InGaAs pseudomorphic HEMTs

The authors investigate the effect of two different gate layouts on the noise characteristics of 0.15*150 mu m² AlGaAs/InGaAs pseudomorphic HEMTs; the T-structure with a gate width of 2*75 mu m, and the multigate finger Pi -structure with a gate width of 6*25 mu m and with airbridges. Whereas the DC characteristics of both types are very similar, the RF noise characteristics of the multifinger gate Pi -structure devices exhibit a minimum noise figure of 0.67 dB with an associated gain of 12.2 dB at 18 GHz, which is superior to that of T-structure devices.