22 GHz performance of the permeable base transistor

Small-signal performance and power performance of GaAs permeable-base transistors (PBTs) at 22 GHz are reported. A small-signal gain of 14.5 dB was demonstrated over a 1-GHz bandwidth from a device having a 3200-AA-periodicity base grating and an 8*20 mu m/sup 2/ active area. A similar device, biased for class AB operation, achieved 45% power-added efficiency with an output power of 83 mW, and an associated gain of 5.7 dB. An output power of 210 mW with 4.7-dB of gain and 37% efficiency were obtained from a larger device having an 8*40 mu m/sup 2/ active area. A pair of these large devices in parallel delivered 370 mW with 3.7 dB gain and 33% efficiency, and 410 mW with 3.1 dB gain and 31% efficiency.<>