Linearization of RF power amplifiers using power feedback

This paper describes a simple and partly new method for linearization of RF power amplifiers using power feedback. Both analysis and experimental results are given. In the analysis, the fundamental properties associated with this scheme are investigated. Advantages and disadvantages are identified and compared with similar linearization techniques. For a given power amplifier characteristics, a simulation method is described to obtain the theoretical limit of reducing nonlinearities with this scheme. Experimental results are also obtained from a prototype linearization system built around a full custom RF analog integrated circuit in CMOS technology that implements the power feedback scheme. When it was tested with an commercially available efficient power amplifier transmitting a NADC (North American Digital Cellular) signal, a reduction of about 10 dB in the adjacent channel interference was achieved. This is in close agreement with the simulation result.