InP DHBT technology optimization for power amplifiers at mm-wave frequencies

An optimized InP Double Heterojunction Bipolar Transistor (DHBT) technology is presented for millimeter-wave power amplifiers at E-band and higher frequencies. Single- and multi-finger transistors with 0.7um emitter width are designed for high frequency and high power applications. The static and frequency performances of the fabricated devices are discussed. Reported cutoff frequency and maximum oscillation frequency are ft=260 GHz and fmax=450 GHz for a 0.7x5um² single-finger device, respectively. Ballasted devices are introduced to improve thermal behaviour and to increase the limits of the safe operating area (SOA). The SOA is improved approximately by 60% for 4-finger devices. A fabricated monolithic microwave integrated circuit (MMIC) at E-band based on InP DHBTs is presented and its performances reported to demonstrate the power capabilities of the optimized technology. The output power level is more than 15.8 dBm using a single matched power cell and the associated power-added-efficiency (PAE) for our matched power cell peaks around 8.8%.