2.2.2 InAlAs/InGaAs HEMTs Grown Lattice Matched to InP

The fastest three terminal devices available are InP substrate HEMTs based on the InAlAs/InGaAs materials system. At the same time 65 % PAE at ${\it f}$= 20 GHz was achieved using lattice matched and pseudomorphic channel material compositions in [307] on InP substrate. With a similar process TRW [131] demonstrated a record setting ${\it P}_{\mathrm{sat}}$= 427 mW at 94 GHz on a single chip. By means of spatial power combining a saturated output power ${\it P}_{\mathrm{sat}}$= 2.4 W in a module at 94 GHz [132] was achieved. Circuits have been demonstrated for frequencies as high as ${\it f}$= 215 GHz reaching into the G-band (140-220 GHz) [313]. Noise figures as low as 2.9 dB have been reported at ${\it f}$= 94 GHz [156] using InP based HEMTs. With a similar process and gate length ${\it l}_{\mathrm{g}}$ = 80 nm, a record setting noise figure of 5.5 dB at 183 GHz in a module was reported in [228]. For a comparison of the reported noise figures especially above 100 GHz, see Fig. 2.5.