Multi-finger 250nm InP HBTs for 220GHz mm-Wave Power

We present here measured DC and RF performance of multi-finger 250nm InP HBTs intended for power amplifier design at high-mm, sub-mm-wave frequencies. The designs presented are in common-emitter and common-base configuration, having 24um periphery. Performance limitations for the PA cell have been identified and mitigated through novel design and layout - they include HBT thermal impedance, RF bandwidths f(t) and f(max), MAG/MSG @ 220GHz, and reduced common-base stability from parasitic base inductance L-b and/or collector-emitter capacitance C-ce. The PA cells are realized using substrate-shielded non-inverted thin-film microstrip wiring to minimize L-b and C-ce, make small the feed lines to the multi-finger devices, and prevent parasitic substrate-mode excitation in the 12.8-epsilon(r) InP substrate.