
114 Gallium Nitride (GaN): Physics, Devices, and Technology
have been limited in the frequency range of <10 GHz mainly due to an insufcient
gain and a limited cutoff frequency necessary for high-efciency switched-mode
operation at higher frequencies. At W-band, the highest PAE reported to date is 24%
[16]. Figure 4.3 shows a comparison of the output power and efciency performance
between various GaN, GaAs, and InP ampliers operating in W-band [15,16]. GaN
HEMT ampliers have comparable PAE and about 3–4 times more output power
than InP HEMT ampliers in this frequency range. To take full advantages of GaN-
based material systems for high-po ...