A 74-GHz bandwidth InAlAs/InGaAs-InP HBT distributed amplifier with 13-dB gain

To date, distributed amplifiers based on heterojunction bipolar transistors (HBT's) have consistently shown lower gain-bandwidth products than their h igh electron mobility transistor (HEMT) counterparts. By using improved des ign techniques, we report in this letter a single-stage distributed amplifi er with 13-dB gain and 74 GHz 3-dB bandwidth, based on InAlAs/InGaAs-InP HB T's with 160-GHz fT and 140-GHz f(max). The high gain and bandwidth results in a gain-bandwidth product of 330 GHz, which is, to our knowledge, the hi ghest reported for HBT-based amplifiers and rivals that of the best InP HEM T distributed amplifiers with e-beam written gate of 0.1-0.15 mu m dimensio n.