Abstract :
Linear Power amplifiers become very a hot issue for the mobile communication. The main focus is high efficiency to reduce cost. The other is the flexibility to handle various services. The meet the requirements, the transmitters are assisted by digital technique. The performance of the unit PAs is improved significantly using GaN technology. The class E, J, F and saturated amplifiers are heavily researched. To improve the performance further, the unit amplifiers are utilized in transmitter architectures such as Doherty amplifier, Envelope Tracking, and class-S, which are assisted by digital circuits. These advanced architectures will be introduced. Finally, the digital predistortion technique will be discussed, which is the main linearization technique of the transmitters.
