Design And Analysis Of Highly Efficient Power Amplifier For Base-Station Application

With the development of the technology,the phone,cordless telephone, WLAN,Bluetooth have been evolving in our daily life, wireless communication is beening rapidly developed.Modern wireless mobile base-station system requires more energy when sending signal to mobile terminals, the system efficiency gets more and more attention, special for power amplifier (PA) as the base-station terminal. Since different countries have adopted diverse standards, there is a variety wireless communication systems. Wireless communication systems employ either envelope-varying signals or constant-envelope signals. The global system for mobile communications (GSM) systems apply constant-envelope signals. Information under these environments is encoded in the phases of signals without changing the amplitudes. Since the PAs for the constant-envelope signals are not required to operate linearly, they are required only to amplify signals efficiently to increase the battery life. In the constant-envelope systems, PAs operate with the output power saturated. The systems using envelope-varying signals are code division multiple access (CDMA), wideband code division multiple access (WCDMA) and Time Division-Synchronous Code Division Multiple Access(TD-SCDMA). These systems modulate the amplitudes of signals to encode more information in the limited bandwidth. Power amplifiers (PAs) working for these systems amplify the input ignals linearly.if the envelope-varying signals are amplified by the nonlinear power amplifer, the signals will be distortion and spectrum regrowth will emerge. Therefore, we need a PA operating as a linear PA for an envelope-varying signal, the traditional PA is desired to operate linearly at the backed-off region from the saturated power, the efficency of the power amplifier is degraded severitily.In the fisrt place, this thesis did theory analysis according to class F PA's structure and Doherty PA's structure, and then separately give an example of class F PA for GSM and Doherty PA for WCDMA base-station application. According to the results, the power amplifier efficiency is highly improved than the traditional Class AB PA.Last, according to the project needments, the Doherty PA is made out and measured, the measurement results shows that the theory agree with the practice results.