High-gain, low-noise monolithic HEMT distributed amplifiers up to 60 GHz

Ultrabroad-bandwidth distributed amplifiers with cutoff frequencies of 45 to 60 GHz were developed using 0.25- mu m high-electron-mobility transistors (HEMTs) with a mushroom gate profile. Both single and cascode HEMTs were used as the active devices in the amplifiers. A measured gain as high as 10+or-1 dB from 5 to 50 GHz and a gain of 8+or-1 dB from 5 to 60 GHz, respectively, were achieved from amplifiers using cascode HEMTs. The measured noise figure for these amplifiers is approximately 3-4 dB in the Ka-band. The chip size is 2.3*0.9 mm. Device considerations, circuit design, monolithic IC fabrication, and the measured performance of the amplifiers are outlined.<>