190-260GHz High-Power, Broadband PA's in 250nm InP HBT

This paper reviews 190-260 GHz solid-state power amplifiers demonstrated in a 250 nm InP HBT technology. The power, gain, and bandwidth achieved by these amplifiers is world class, and due to the high gain, bandwidth, and breakdown voltage associated with the transistor technology. The use of a cascode-cell PA topology permits highest W/mm to be achieved from the HBT at these frequencies, as well as high MMIC gain. Through the use of thin-film microstrip, broadband 2:1 and 4:1 power combiners with only 0.5 dB insertion loss are available. A 4-PA cell design has demonstrated 70 GHz of large-signal bandwidth between 190-260 GHz, with Pout ranging between 47- 80 mW. The 4-PA cell design may be stacked to realize 8-, and 16-PA cell designs for higher output power. A 16-PA cell design has demonstrated 220 mW Pout at 200 GHz and 208 mW at 210 GHz. Reported for the first time here are new designs (Gen-2) that have been aggressively scaled in size vertically to realize higher power PA's in a given form-factor. This is necessary to prevent reductions to the PA bandwidth as cells are progressively combined.