Power amplifiers are among the most important of components for modern wireless communications systems. Ideally, they can provide high output power with high linearity and high efficiency. But tradeoffs typically occur among these three key power-amplifier performance parameters, and amplifiers with the highest output power and linearity usually sacrifice linearity.
In modern telecommunications systems supporting wide bandwidths and high data rates, transmitted signals are usually characterized by high peak-to-average power ratio (PAR) due to wide and rapid variations in the instantaneous transmitting power. Therefore, it is a challenge to design a wireless base-station power amplifier having high efficiency not only at maximum output power, but at lower power levels typically ranging from 6 dB and less of the maximum power level, with minimum size and lower cost of implementation.
However, the problem is solvable by using gallium-nitride (GaN) high-electron-mobility-transistor (HEMT) device technology and innovative Doherty amplifier architectures. It’s possible to achieve 60% average efficiency and reduced power consumption for average output-power levels of 100 W and higher.