Backside process free broadband amplifier MMICs at D-band and H-band in 20 nm mHEMT technology

High gain amplifier MMICs (monolithic microwave integrated circuits) addressing broadband radar and communication applications at the waveguide bands WR-6 (110 - 170 GHz) and WR-3 (220 - 325 GHz) are presented. All circuits are manufactured in the next generation metamorphic high electron mobility transistor (mHEMT) technology featuring 20 nm gate length and a strained 100% InAs channel. The transistors are encapsulated by 0.3 µm and 1.4 mm thick layers of benzocyclobutene (BCB). The 1.4 µm thick BCB layer is used to form shielded thin-film microstrip (TFMS) lines confined at the front-side of the wafer for implementing matching networks. Substrate thinning and backside processing is not required for the function of the amplifiers. The amplifier for WR-6 operates over the whole waveguide band with an average gain of 28 dB. A gain of more than 24 dB was measured for the MMIC from 215 - 290 GHz. All presented MMICs exceed 30% of gain defined bandwidth.