Research And Design Of X-band Wide Pulse High Power Internal Matched Power Amplifier

With the advent of the 5G era,the communications industry has maded another great development.GaN power devices,as the key element in the communication field and semiconductor field,have also been developed and applied to a new level.GaN is the most promising semiconductor compound in the third generation of wide band semiconductor materials,with large forbidden band width,high electron mobility.It aiso has high saturation electron velocity,high critical breakdown field strength characteristics.GaN has good heat resistance to meet the demand of high voltage,high current,and high power density device design,which has good application prospects in the direction of high power and high efficiency microwave power device design.Featuring small size,light weight,low loss,high gain and good stability,internally matched power amplifiers have become key devices in communication base stations as well as transceiver components.The thesis is based on a domestic GaN HEMT to design a high-frequency high-power internal matching amplifier.The main research contents are as follows:The characteristics of the third-generation semiconductor GaN materials and the development and current status of GaN devices is contrasted and analyzed by the thesis,demonstrating the development advantages of GaN devices in the 5G era.The amplifier design uses high-power density and high-voltage GaN die.The die adopts a multi-cell structure to disperse heat distribution.Through the multi-cell die synthesis technology,a wide pulse and high-power output is realized.The work on testing the DC characteristics and stability of GaN cores and selecting the voltage loading conditions at both ends of the system according to the core characteristics is described in this thesis.The design of the matching circuit is realized by the ADS software.The input and output matching circuits are constructed based on the core impedance values,which are obtained by multiple iterations of each other using the load-pull and source-pull methods.A four-way parallel structure is used to design a matching circuit,and a T-shaped matching network is built through capacitors,key alloy wires,and microstrip lines.Then the input power combiner and the output power divider are designed to connect the input and output matching network,complete the construction of the entire internal matching circuit,match the die impedance to 50?,and connect it to the port.By the simulation of the ideal components of the internal matching circuit,the output power,gain linearity and additional power efficiency of the circuit are optimized.After the optimization is completed,the schematic diagram is replaced with the component layout,electromagnetic field simulation is performed,and the layout structure is adjusted to achieve the predetermined performance indicators.The input and output bias circuit are designed to avoid the mutual influence between microwave and voltage circuit,and isolate the influence of the second harmonic on the circuit.After completing the design and optimization,tape out power dividers,capacitors and other devices,and design and manufacture tube cases and test fixture boxes.Sinter the internal matching circuit inside the tube shell adjust the size of the capacitor and the key alloy wire,and debug the best performance of the amplifier.A test system is built,and the test proved that the output power of the amplifier is greater than 250 W under the condition of a frequency range of 9.5 to 10.5 GHz,a pulse width of 200 ?s,and a 10%duty cycle,whereas the power added efficiency is higher than 35%,and the power gain is greater than 8 dB.Finally,a fourth-order deformed hairpin microstrip filter with a center frequency of10 GHz and a passband width of 1GHz was designed according to the experimental needs.The HFSS software was used for modeling and simulation,and its insertion loss,return loss,and out-of-band suppression were optimized.The test proves that the center frequency of the filter is 10 GHz,the passband range is 9.5GHz?10.5GHz,the insertion loss is less than 2dB,the return loss is greater than 15 dB,and the out-of-band suppression is greater than 30 dB.A prototype is fabricated and tested,providing a satisfactory agreement with the simulated results.