The Research Of Millimeter-wave Linearization Technology

Millimeter-wave communication technology has been highly developed in the past few decades,with its strategic position at military field.Making use of millimeter-wave technology apply into 5G mobile communication system,to realize the multi-user,high capacity,high data rate,miniaturization of modern communication system is a generally recognized vision in the industry.Complex modulation techniques are often used to improve the spectrum efficiency in those current millimeter-wave communication systems.In order to reduce the system cost,amplifiers of final stage often operate at the strong non-linear area to ensure high efficiency.Faced with the serious challenge,many linearization techniques were proposed to ensure the linearity of the amplifier.Among them,analog predistortion is one of the research hotspot.In this paper,the analog predistortion linearization technique based on schottky diode is discussed combined with the non-linear characteristic of travelling wave tube amplifier(TWTA).The main research contents of this paper are as follows:Firstly,a Ka-band transmission-type predistortion linearizer is developed using a parallel schottky diode structure.The result showed that the predistortion linearizer could provide 0~8 d B variable gain compensation and 0~40 degrees variable phase compensation in the working frequency range.The P1 d B of the target TWTA has been improved by 1.7~2.7 d B and the phase distortion has reduced to 3.5~13 degrees.The third-order intermodulation coefficient(IMD3)has improved by 7.1~15.4 d Bc at-7 d B IBO per carrier.Then,based on the study of reflection-type predistortion linearizer,a Ka-band reflection-type broadband predistortion linearizer is developed.The operating frequency band is 30~34 GHz.The linearizer has a good performance.With the input power of 20 d B dynamic range,at the center frequency,the pre-distortion linearizer can provide 7.5 d B variable gain compensation and 70 degrees phase compensation.Finally,based on the reflection predistortion linearizer,a new structure of two-way synthesized is proposed.The attenuator and the phase-shifting network are used to realize the control of the predistortion signal.The experimental results show that,the structure can realize a continuously adjustable phase compensation in the range of-60 degrees to 60 degrees with almost no change in its gain compensation curve.This kind of structure is extremely tunable and adaptable,and it can be applied to both travelling wave tube amplifier(TWTA)and solid-state power amplifier(SSPA).