Research And Design Of Millimeter-wave Analog Linearizer

In recent years,the field of global communication satellite is booming.To meet the requirements of high-speed and large capacity for satellite communication system,high-efficiency modulation technology develops rapidly,and further improving the utilization rate of frequency band.On the other hand,the frequency band of satellite communication gradually develops to millimeter-wave Ka,V,Q,W frequency band,and further obtaining more available spectrum resources.However,with the increase of communication frequency and the application of high-efficiency modulation technology,the requirements of communication system for basic functional devices are higher and higher.In the whole satellite communication system,linear amplification is needed to demodulate the modulation signal accurately.However,to obtain high power output,the final stage power amplifier usually needs to work in the saturation region,which often causes serious nonlinear distortion to the modulation signal and increases the bit error rate.Analog predistortion linearizer is the key device to improve the linearity of power amplifier and keep its high output power and efficiency.It has been widely used in microwave frequency band and millimeter wave low-end frequency range.However,in higher frequency band,such as W-band,there is no unified design method,and the design experience is seriously insufficient.Therefore,this paper focuses on the theoretical analysis and design of analog predistortion linearizer for E-band(81-86GHz)and W-band(92.5-97.5GHz)TWTAs.Aiming at the W-band(92.5-97.5GHz)analog predistortion linearizer,a new design method of "field circuit combination" based on the three-dimensional electromagnetic simulation model of Schottky diode is proposed in this paper.The design scheme of bridge reflective analog predistortion linearizer based on Schottky diode is adopted,and a W-band analog predistortion linearizer is realized for the first time in China.It can achieve gain expansion ? 5.9dB and phase expansion ? 26.5 °,and the expansion has voltage adjustable characteristics,which can be applied to TWTA with different non-linear characteristics.The difficulties in the development of high frequency analog predistortion linearizer have been successfully overcome.Aiming at the E-band(81-86GHz)analog predistortion linearizer,a bridge reflection analog predistorter based on Schottky diode is realized by the improved design method of "field circuit combination".It can achieve gain expansion ? 5.1dB and phase expansion ? 46.3 °.Based on this linearizer,an E-band TWTA linear power driver module is developed for the first time in China.When the dynamic range of input power is 30 dB,the gain expansion ? 6.2dB and the phase expansion ? 47.8 °,and its small-signal gain adjustable performance is excellent.It can achieve 20 dB adjustment range,and can match with TWTA flexibly.It is of great significance for the further application of high-frequency linearizer.