Research On Millimeter-wave Analog Predistortion Technology

Linearizers are the key-components in millimeter-wave communication systems and are critical to improving the linearity of amplifiers and improving communication qual-ity.The analog predistorter has a simple structure,good effect and easy engineering.By studying the analog predistortion technology,the power amplifier can achieve better lin-ear power and phase characteristics with higher efficiency.Solid state power amplifiers?SSPA?and traveling wave tube amplifiers?TWTA?are the most common core devices in the millimeter wave power module?MMPM?.At present,high-power SSPAS are mainly realized by GaN devices,and TWTAS have also been developed to work in bands such as V,E,and W.With the development of technologies such as satellite communications and electronic countermeasures,these devices are required to have better linearization characteristics.In this thesis,the theoretical pre-distortion circuit based on GaAs planar Schottky diode technology is analyzed theoretically.An accurate Schottky diode model combined with 3D electromagnetic field analysis is established.The model is used for Ka-band GaN SSPA and W-band traveling waves.The tube amplifier has been pre-distorted circuit design and experimental verification.The research work done in this paper can be used to improve the nonlinear characteristics of amplifiers such as millimeter-wave solid-state power modules or space traveling wave tubes.In order to meet the linearization requirements of GaN power modules,this thesis de-signs an analog predistortion linearizer for 27GHz³1GHz GaN SSPA based on two-way synthesis structure for 8mm GaN solid-state power amplifier.The linearizer has a gain expansion of more than 3dB in the range of input power of-10dBm,and phase compres-sion can reach more than 20°.When the input power is increased to more than 3dBm,the gain expansion and phase compression efficiency are 7dB and 50°.The linearizer's linear output power can reach 25dBm,which can be used to improve the nonlinear distortion characteristics of the power amplifier with input power requirements below 25dBm.The output P_1dBof the GaN power amplifier after the cascaded linearization driver amplifier is improved by 2dB.When the power amplifier output is 2¹2dB of saturation power back-off,the third-order intermodulation of the GaN power amplifier is improved by 3¹5dB.This thesis is designed to implement the analog predistorter for TWTA in the W band,which can meet the linearization requirements of space traveling wave tube amplifier in W band satellite communication.To improve the design accuracy,this paper considers the W band.The parasitic parameters introduced by the planar Schottky diode are used to establish a three-dimensional electromagnetic field model of the diode.A transmission-type dual-tube analog predistortion circuit based on the fin structure is proposed,which solves the nonlinear adjustment of the traditional reflective predistorter.The disadvantage of small amplitude is that the gain expansion can reach more than 9dB in the range of82.5GHz⁸7.5GHz,and the phase expansion can reach more than 30°.the test can achieve a gain expansion of more than 20dB and a phase expansion of 130°or more at 82GHz.