Linearization Technology Research For Millimeter-wave Power Amplifier

With the development of modern wireless communication technology,complex digital modulation schemes are widely used in modern wireless systems in order to cope with the rapid growth of terminal devices and high volume data.The signal adopting these modulation schemes tends to have a higher peak-to-average power ratio,which easily drives the power amplifier into saturation and generates nonlinear distortions.Therefore,power amplifiers with higher linearity are demanded.Meanwhile,in the wireless system,power amplifiers usually operate near saturation in order to achieve good efficiency,which will generate great distortions due to their strong nonlinearity.Various linearization techniques have been proposed to compensate these nonlinear distortions,and linearization of power amplifiers has become a focus of microwave and millimeter-wave technology study.This thesis focuses on linearization technologies of power amplifiers,and the main contents of this thesis are as below.In this thesis,the nonlinear characteristics of the power amplifier are theoretically analyzed,and the mainstream linearization techniques are compared by their operating principles,applications,advantages and disadvantages.This thesis mainly studies the nonlinear predistortion techniques of Ka-band solid-state power amplifier(SSPA),and based on the nonlinear characteristics of Schottky barrier diodes and vector synthesis theory of reflection coefficients,a novel reflective analog predistortion circuit is proposed to compensate the nonlinear distortions of SSPAs,which could not be accomplished by traditional reflective approach.Based on the proposed circuit,a Ka-band balanced reflective predistorter achieves gain expansion of 2.8-3.2dB and phase compression of 6.4-20.1~°at 30GHz,and another Ka-band one-way reflective predistorter achieves gain expansion of2.2-3.9dB and phase compression of 1.5-30.5~°at the same frequency.A Ka-band balanced predistorter is implemented using a 0.15μm GaAs monolithic integrated circuit process,and in the frequency range of 27-33GHz,the gain expansion of 3.39dB and phase compression of 17.31~°are achieved.Finally,by adding front and rear driving circuits properly,a balanced Ka-band reflective predistortion drive module is designed based on the proposed one-way reflective predistorter above.