Research Of K-Band Power Combining And Linearization Technology

As a key components in modern communication systems,solid-state power amplifiers develop in high power,high frequency and high efficiency direction.Their performance is critical to the communication systems.The output power of a single device is limited,so power combination echnology is used to achieve greater output power.As the input power increases,the power amplifier gradually enters a non-linear working state and has a nonlinear distortion phenomenon which seriously affects the performance of the power amplifier.Therefore,in order to ensure that the amplifier can achieve higher output power and better linearity at the same time,linearization technology comes into being.The first part of the thesis is the study of diode-based predistortion linearizers.The nonlinear characteristics of the parallel Schottky diode analog predistortion linearizer is studied for the nonlinear characteristics of the solid state power amplifier.We have theoretically analyzed the temperature response of the linearizer and propose a temperature compensation method.By adjusting the bias voltage of the diode,the equivalent resistance does not change with temperature to achieve temperature invariant.The simulation results show that the gain and phase of the linearizer with temperature compensation circuit varies little with increase of temperature.The pre-distortion linearizer has the advantages of simple structure and good stability.The second part of the thesis is the study of the K-band power combiner.Firstly,we finish the design and simulation of the waveguide to microstrip transitions.After the transition is determined,three power combiners are designed.The main works in this thesis are summarized as follows:We have improved the traditional T-waveguide which transition waveguide and triangular tip have been added.This structure can greatly improve the matching.The simulation results show that the power combiner's insertion loss is less than 0.3dB and return loss is better than 24 dB from 20 GHz to 22 GHz.Based on the 3dB branch waveguide directional coupler,the straight-through ends of the two couplers are combined.The amplitude and phase of the three output ports are adjusted by optimizing the coupling hole size.The simulation results show that the insertion loss of the power combiner is less than 0.5dB and the return loss is better than18 dB over the working frequency range.For non-binary power combiners,this structure performs well.The electromagnetic field in the radial waveguide is theoretically analyzed.Based on this theory,an eight-way power divider is designed.Multi-stage ladder structure is added at the bottom of the radial waveguide to achieve impedance matching.The simulation shows that it meets the design requirements of low reflection and low loss.After back-toback connection,the insertion loss of the whole structure is less than 0.6dB and the return loss is better than 14 dB,which achieves the design goal.