Millimeter Wave Power Amplifier Linearization Technology Research

In mobile and satellite communication systems, power amplifier is one of the most important component, whose good performance is essential to the entire system. Efficiency and linearity of the PA is a pair of critical but conflicting indicators. When the input of the power amplifier increases to a certain value, the phenomenon of nonlinear distortion occurs. When the power amplifier is saturated, the efficiency is the highest, while the nonlinear distortion is the most serious. The rapid development of modern communication technology asks the output power and the linearity of the system to be higher at the same time.With the frequency resource of the RF and microwave band becoming increasingly crowded, the millimeter-wave technology has been developed greatly in recent years. However, the linearization development of power amplifier in millimeter-wave band can hardly be seen, especially domestic. Based on Schottky diode and analog pre-distortion we do some research work on PA linearization in millimeter-wave band and finally get what we expected originally.In this paper, the nonlinear distortion character and some critical indicators are analyzed, and then several common linearization techniques are introduced. On this basis, the design scheme is put up:1. Based on two Schttoky diodes and co-planar waveguide, the analog pre-distorter, operating in Ka-band, is put forward. The test results, using vector network, verify the nonlinear distortion character is gain expanded and phase compressed in25-38GHz. And applying the pre-distorter to a PA (2W), the IMD3of the PA is improved as we expected.2. Based on rat-race ring hybrid, a20W power combining amplifier, operating in29-31GHz band, is put forward. Then we do some pre-distortion processing to it using the pre-distorter which is put forward before, and finally a Ka-band linearized high power amplifier is designed.The pre-distorter put forward in this paper is simple in structure and low in cost, so it is certainly practical. And it is the first time to realize broad-band analog-predistortion in mm-wave band.