Monolithic low noise amplifiers using 0.15-pm Al-GaAdInGaAdGaAs pseudomorphic HEMTs with a passivation film have been developed at I.17-band for the Advanced Microwave Scanning Radiometer. A two-stage monolithic amplifier has achieved a noise figure of 3.4 dB with a small signal gain of 8.7 dB at 91 GHz. A six-stage amplifier cascading three twostage monolithic amplifier chips has achieved a noise figure of 4.2 dB with a small signal gain of 29.7 dB at 91 GHz. Taking into account the minimum noise figure of 2.5 dB with an associated gain of 4.3 dB of 0.15 x 60 pm2 PHEMTs at 90 GHz, these results demonstrate that a good noise matching has been successfully achieved.