Research On 2-6GHz Ultra-wideband Linearization Technolog

In recent years,satellite communication systems are moving in the direction of large capacity,high speed,ultra bandwidth,microwave millimeter wave frequency band as a vital part of the satellite communication frequency band,faced with the frequency resources increasingly tense problem,with some complex modulation technique is widely used,linearity,and bandwidth of communication system puts forward higher requirements.The linearity of the system is mainly affected by the final high power amplifier,so the ultra-wideband power amplifier linearization technology has broad application prospects and great research value.However,the existing power amplifier linearizers are seldom used in UWB systems.In this paper,based on the analog predistortion technology,an UWB linearizer working at 2-6GHz is proposed.In the ultra-wideband linearizer,a reflective parallel reverse diode pair pre-distortion circuit is used to improve the gain expansion and phase compression capabilities of the nonlinear generator.A 90° coupler based on DGS structure is designed to extend the bandwidth of the traditional microstrip coupling line coupler to 2-6GHz.A kind of analog phase shifter based on varactor diode is designed.By cascading two varactor diodes on a transmission line,the maximum electric phase shift of the phase shifter is improved.The key components such as power divider attenuator and driver amplifier are UWB.The result is gain expansion of more than 6dB in the 2-6 GHz frequency range,with 30° phase compression.Secondly,a UWB power amplifier based on CGH40006P GaN HEMT transistor is designed,and its UWB input and output matching network is realized by using stepped impedance matching,gradient line impedance matching and open branch matching techniques.The UWB power amplifier has a saturation output power of 37.4-39.4dBm,a saturation gain of5.4-7dB,and a saturation drain efficiency of more than 50%.Finally,the power amplifier and the linearizer are cascaded and verified.The final test results show that the UWB linearizer can provide 1.5-3.1dB gain expansion in the bandwidth of 2-6GHz,and the third-order intermodulation improvement can reach 8dBc,showing excellent performance.