GaN HEMT: Dominant Force in High-Frequency Solid-State Power Amplifiers

The gallium nitride (GaN) high-electron-mobility transistor (HEMT) has emerged as the dominant force in high-frequency solid-state power amplifiers (PAs)-not that it does not have competition. Silicon (Si) bipolar junction transistors (BJTs) and Si laterally diffused metal-oxide-semiconductor (LDMOS) field-effect transistors (FETs) are still commercially available. They are viable alternatives to GaN HEMTs in aerospace/defense applications such as L-band transponders/interrogators for the identification friend or foe; Link 16 data links; electronic warfare; and surveillance radar; and, in the case of Si LDMOSs, commercial cellular base stations. These older technologies can be favored due to their mature heritage, good performance, and low cost. The pseudomorphic HEMT (PHEMT) is ubiquitous in microwave and millimeter-wave power applications. Vacuum electron devices (VEDs) still reign in the regime of brute power. The GaN HEMT has been displacing these technologies as it has matured and costs have come down.