A coplanar 94 GHz low-noise amplifier MMIC using 0.07 µm metamorphic cascode HEMTs

A 94 GHz low-noise amplifier MMIC (LNA) has been developed, based on a coplanar technology utilizing 0.07 µm depletion type metamorphic HEMTs (MHEMTs). The realized single-stage cascode LNA achieved a small-signal gain of more than 12 dB and an average noise figure of 2.3 dB over the bandwidth from 80 to 100 GHz. With an indium content of 80 % in the channel a 2 x 30 µm MHEMT device has shown a transit frequency (ft) of 290 GHz, an extrinsic transconductance of 1450 mS/mm and a maximum stable gain (MSG) of 11 dB at 94 GHz. Using two HEMTs connected in cascode configuration the MSG could be increased to 22 dB. To stabilize the cascode device and to increase the bandwidth of the amplifier circuit a resistive feedback was integrated into the HEMT in common-gate configuration. Coplanar topology in combination with cascode transistors resulted in a chip-size of only 1x1mm2.