A quantitative comparison of multiline TRL （thru-reflect-line） and LRM （line-reflect-match） on-wafer calibrations for scattering parameters （S-parameters） measurement of InP-based PHEMTs is presented. The com- parison is undertaken for the first time and covers a frequency range from 70 kHz to 110 GHz. It is demonstrated that the accuracy of multiline TRL and LRM calibration is in good agreement. Both methods outperform the conven- tional SOLT calibration in the full frequency band up to 110 GHz. Then the excellent RF performance is obtained by extrapolation on the basis of inflection point, including a maximum current gain cut-off frequency ft of 247 GHz and a maximum oscillation frequency fmax of 392 GHz. The small-signal model based on LRM calibration is es- tablished as well. The S-parameters of the model are consistent with the measured from 1 to 110 GHz.
90-nm T-shaped gate InP-based In_（0.52）Al_（0.48）As/In_（0.6）Ga_（0.4）As pseudomorphic high electron mobility transistors were designed and fabricated with a gate-width of 2×30 μm,a source-drain space of 2.5 μm,and a source-gate space of 0.75 μm.DC,RF and small-signal model characterizations were demonstrated.The maximum saturation current density was measured to be 755 mA/mm biased at V_（gs）=0.6 V and V_（ds）=1.5 V.The maximum extrinsic transconductance was measured to be 1006 mS/mm biased at V_（ds）=—0.1V and V_（ds）=1.5 V.The extrapolated current gain cutoff frequency and maximum oscillation frequency based on S-parameters measured from 0.5 to 110 GHz were 180 and 264 GHz,respectively.The inflection point（the stability factor k=1）where the slope from-10 dB/decade（MSG） to-20 dB/decade（MAG） was measured to be 83 GHz.The smallsignal model of this device was also established,and the S-parameters of the model are consistent with those measured from 0.5-110 GHz.
83-nm T-shaped gate InP-based In0.52Al0.48As/In0.65Ga0.35As pseudomorphic high electron mobility transistors （PHEMTs） with excellent DC and RF performance as well as low noise characteristics are reported, including a maximum saturation current density/ass of 894 mA/mm, a maximum extrinsic transconductance gm, max of 1640 mS/mm, an extrapolated cutoff frequency ft of 247 GHz and a maximum oscillation frequency fmax of 392 GHz which were based on the measured S-parameters from 1 to 110 GHz. The minimum noise figure （NFmin） measured by the cold-source method is 1 dB at 30 GHz associated with a gain of 14.5 dB at Vds of 0.8 V and Ids of 17 mA. These results were obtained by the combination of increased InAs mole fraction in the channel, gate size scaling, parasitic reduction and the quantization channel. These excellent results make it one of the most suitable devices for millimeter wave （MMW） low noise applications.
