A monolithic Ka-band HEMT low-noise amplifier

A monolithic, single-stage HEMT low-noise amplifier has been developed for the 20-40-GHz band. it includes a single 0.25- mu m-gate-length HEMT active device with on-chip matching and biasing circuits. A gain of approximately 6 dB from 20 to 38 GHz and a noise figure of approximately 5 dB from 26.5 to 40 GHz were measured. Replacing the triangular gate profile by a mushroom gate profile in the amplifier increased the measured gain to 8 dB from 20 to 37 GHz and reduced the measured noise figure to 4 dB from 26 to 40 GHz. These are the best reported results for a MMIC amplifier over this bandwidth. The chip size is 2.2 mm*1.1 mm. The same amplifier was fabricated on pseudomorphic HEMT material with a triangular gate profile and achieved 7.5-dB gain across the 20-35-GHz bandwidth and a 6.0-dB noise figure from 26.5 to 40 GHz. The measured 1-dB compression powers at 30 GHz for the conventional and pseudomorphic HEMT amplifiers are 10 dBM and 11.5 dBM, respectively, when biased for maximum power.<>