250 nm InP DHBT monolithic amplifiers with 4.8 dB gain at 324 GHz

An indium-phosphide (InP) double-heterojunction bipolar transistor (DHBT) based common-base monolithic power amplifier has been fabricated and has a measured small signal gain of 4.8 dB at 324 GHz. This is the highest frequency DHBT MMIC amplifier reported to date. The submillimeter-wave power amplifier MMIC incorporates microstrip transmission lines on a 10-mum thick layer of BCB dielectric. The thick BCB layer provides mode-free low-loss millimeter-wave transmission lines without requiring a thin fragile InP substrate and through-wafer vias as with conventional microstrip placed directly on the semiconductor substrate. The single-stage power amplifier has a compact size of only 0.124 mm² and a measured saturated output power of 1.3 milliwatts with a dc input power of 1.4 V at 12 mA. These results demonstrate the capability of 250 nm InP DHBT technology to enable power amplifiers for submillimeter-wave applications.