Metamorphic HEMTs developed by OMMIC have been DC- and RF-characterized. An extrinsic DC transconductance of 770 mS/mm was obtained for a 4x25Âµm MHEMT. Typical extrinsic unity current cut-off frequency; fT; was 140 GHz with a maximum oscillation frequency of 196 GHz. Broadband three-stage amplifiers utilizing these transistors were designed fabricated and characterized for various frequency bandwidths up to 90 GHz. For the 26-43 GHz bandwidth; the amplifier exhibited a gain of typically 25 dB and a return loss less than 5 db.