The use of Gallium Nitride (GaN-on-SiC) technology in high performance RF power amplifiers (PAs) is now widespread. Whilst the cost per unit area of GaN is still higher than that of competing technologies such as Gallium Arsenide (GaAs) or LDMOS, the technology has now matured to the point where the transistor cost per Watt of RF output power is lower than GaAs. Active phased-array radars can contain hundreds of amplifiers, so any cost reduction that can be achieved on a single amplifier quickly adds up to significant cost savings. At the same time, the RF performance of the system is paramount, and power amplifiers that use GaN-on-SiC transistors have achieved excellent power and efficiency.