Research On Techniques Of Millimeter Wave Broadband Mixing And Solid-state Power Combined Amplifier And Linearization

Millimeter-wave mixers and solid-state power sources are the core components in systems such as millimeter-wave radar,communications,and test instruments.The wideband frequency response characteristic of the mixer is one of the most important factors affecting the performance of the wideband receiving system.The output power,wideband amplitudefrequency characteristics and linearity of the solid-state power source are the key factors that determine the function of transmitting systems and their performance.In this paper,techniques of millimeter-wave broadband mixer,solid-state high-power combined amplifier and solid-state power amplifier linearization are intensively studied.Firstly,based on Schottky diodes,the IF bandwidth expansion technology in the millimeter-wave balanced mixer circuit is investigated and applied to the development of the V-band wide IF mixer.In order to realize the high-power solid-state power source in E-band,the multi-channel waveguide power dividing/combining network and the power combining technology of high-power solid-state power amplifier are intensively studied.Based on E-band GaAs and GaN power amplifier chips,the prototypes of high-power solid-state combined amplifiers with continuous wave Watt-level and 10 Watts level are successfully developed,respectively.Meanwhile,in order to improve the linearity of the output power of the E-band GaN power amplifier,a reflective analog predistortion circuit is explored in depth.The main research progress of this paper includes the following aspects:1.In order to widen the IF bandwidth of the millimeter-wave broadband mixer based on Schottky diodes,an integrated design of a broadband RF/LO matching circuit and an ultra wideband IF grounding circuit,which combinines multiple short-ended stubs and stepped impedance lines,is proposed.Based on the accurate 3-D model of the diode,the main causes of the IF power nulls are analyzed by the combination of HFSS and ADS,and the influence of the number of IF short-ended stubs on the peak point of the conversion loss is studied.Based on the LO anti-phase balanced fundamental mixing circuit,commercial diodes(MA4E1310)are selected,and a V-band full-band broadband mixer is designed.By optimizing the number and size of the IF short-ended stubs and the spacing between adjacent stubs,the output power nulls in the ultra-wide IF bandwidth are eventually removed,and the wide IF characteristic of the mixer is realized.The experimental results reveal that when LO/RF frequency is50GHz～75GHz,and IF frequency is 0.01GHz～22GHz,the optimal LO input power of the mixer is typically 15 dBm,the conversion loss is 6.8dB～11.4dB,and the RF input P1 dB is greater than 10.7dBm,which verifies the effectiveness of the proposed method of extending the IF bandwidth of the millimeter-wave mixing circuit.2.An effective analysis method for a three-way waveguide power dividing/combining network with arbitrary power division ratio composed of six-port branch-waveguide coupler is proposed based on the principle of odd-even mode.The three-way waveguide power dividing/combining structure based on the six-port branch-waveguide coupler is adopted to solve the problem of limited flexibility in the selection of the number of combining channels in the traditional waveguide binary combining network.Firstly,the six-port branch-waveguide coupler is simplified into two sets of equivalent four-port network models.According to the required operating bandwidth,the appropriate number of waveguide branches is selected,and the network parameters corresponding to different coupling ratios are derived based on the principle of odd-even mode.The classical analytical method is used to obtain the initial dimensions of the branch-waveguide coupler.Then,the HFSS 3-D electromagnetic simulation models of two groups of four-port waveguide networks are established respectively,and the key dimensions are simulated and optimized.Finally,according to the optimized results of the sizes of the above two groups of equivalent networks,a six-port branch-waveguide coupler simulation model is established,and the optimization of the two groups of waveguide branch structures is carried out.In order to ensure the phase consistency,a phase compensation structure in the form of multiple stepped waveguides is designed on the middle channel.Using this technology,two sets of experimental samples of waveguide power splitters with high isolation and equal amplitude outputs in E-band are fabricated.In the frequency band of68GHz～80GHz,tested insertion loss of the back-to-back structure is 0.94 dB～1.67 dB.Using the E-band power amplifier MMIC chip g APZ0051 A,three E-band power amplifier modules are designed.The power amplifier modules and two sets of three-way waveguide power dividing/combining networks are integrated to form a three-way power combined amplifier.Measured results show that in the frequency band of 68GHz～76GHz,the saturated output power of this power combinied amplifier is in the range of 0.9～1.1W.Typical value of the combining efficiency is 75%,and the maximum combining efficiency is 86.6%.3.An E-band broadband high power matching load based on double-sided TaN resistive film is proposed,and a distributed high power absorption load with 16 elements is developed and applied to the output power test system of E-band high power solid state power source.Firstly,the HFSS model of the matched load cell based on the alumina ceramic substrate coated with the graded transition TaN resistive film on both sides is established.In order to achieve good port matching and power absorption performance,the key dimensions of the absorption film are optimized.Then,using a four-level binary power division network,a group of distributed absorption high power matching load is composed of sixteen matching load units.The electrical performance and thermal distribution characteristics are simulated and optimized.Test results show that the return loss of the four-way combining matching load is better than20 dB.Under the conditions of room temperature and natural convection,simulation results shows that when the input power of the 16-channel high power matching load is 30 W,the surface temperature of the module is 37.4℃,the maximum temperature of the TaN film unit is318.7 ℃,which is lower than the maximum temperature 350 ℃ that the TaN film can withstand.Measured results show that when the power loaded on the 16-channel combining matching load reaches 28 W,the surface temperature of the entire matching load is in the range of 35℃～45℃.4.Combining the waveguide E-plane three-branch power divider/combiners,E-plane twobranch power divider/combiner and waveguide 3dB couplers,a 12-way hybrid waveguide power dividing/combining network in E-band that takes insertion loss and isolation into account is proposed and applied to the research of 12-way high power solid state power combining amplifiers in E-band.Using HFSS software,simulation designs of the waveguide E-plane threeway splitter/combiners,the E-plane T-junction power divider/combiner and the waveguide fivebranch 3dB couplers are carried out respectively.Using hybrid integrated circuit technology,a number of single-chip power amplifier modules with a typical saturated output power of 3W are fabricated using GaN MMIC power amplifier chip.Then,three power amplifier modules with good performance consistency are selected and combined with the E-plane three-way power divider/combiner.Experiments of the three-way power combinied amplifier assembly are carried out.The center frequency is a specified one in E-band with a bandwidth of 5GHz,the measured saturated output power is within the range of 5.8W～9.7W,and the combining efficiency is 79.6%～95.8%.On this basis,using 3dB couplers and two sets of three-way combining amplifiers,the experimental study of six-way combining amplifier is carried out.Measured results shows that in the same bandwidth,the saturated output power reaches11.2W～15.8W,and the combining efficiency is 64.6%～80.8%.Finally,using the waveguide Ttype power dividing/combining network,two groups of six-way combining amplifiers are integrated,and the experimental study of twelve-way high power combinied amplifiers is completed.The system design and engineering implementation problems such as system structure layout,power management,heat dissipation,and high power test system construction are solved.Measured results show that the saturated output power of the twelve-way combining amplifier system is 20.8W～27.9W,the combining efficiency of the last stage is 89.4%～93.8%,and the total combining efficiency is 63.3%～71.7%.5.In order to enhance the power capacity of the analog predistorter,a reflective analog predistortion linearization circuit scheme is proposed,in which the reflection branches are loaded with two pairs of Schottky diodes in parallel in the same direction.Using the equivalent circuit model of the MA4E1310 Schottky diode,a theoretical model of nonlinear characteristics of a single-branch dual-diode reflective analog predistortion linearizer based on a waveguide3 dB coupler is established,and the gain amplitude expansion,phase expansion and compression characteristics under different DC bias conditions are analyzed.Using the simulation analysis method based on the combination of HFSS and ADS softwares,the amplitude and phase characteristics of the E-band predistortion linearizer under different bias conditions are investigated,the circuit and structural parameters are optimized,and experimental sample is fabricated.Measured results show that the linearizer exhibits two different amplitude and phase characteristics under different DC bias conditions.When the DC voltages loaded by the two pairs of Schottky diodes are +10V and-6V respectively,in the frequency band of 74GHz～78GHz,the gain amplitude expansion is 3dB～6.7dB,and the phase expansion is 21.4°～30.7°.When the DC voltages loaded by the two pairs of Schottky diodes are close to +0.75 V and +0.55 V respectively,in the 74GHz～76GHz frequency band,the gain amplitude expansion is 1.5dB～2.5dB,and the phase compression is 10.4°～20.2°.Using such characteristics,it can be used as a linearizer for both solid-state power amplifiers and traveling wave tube amplifiers.6.Using the amplitude expansion and phase compression characteristics of the above linearizer,experimental study on the linearization of the amplitude and phase characteristics of the E-band 3W GaN solid state power amplifier is carried out.In order to make the nonlinear curves of the linearizer and the power amplifier module obtain a better complementary effect,a linearization driving component by cascading gain adjustable modules at the input and output ports of the linearizer is formed,and it is cascaded with the GaN solid state power amplifier module to form an E-band GaN solid state power amplifier analog predistortion linearization experimental system.E-band single-tone signal and the two-tone signals with a frequency interval of 10 MHz are used to measure the output power and third-order intermodulation characteristics of the final stage power amplifier,respectively.Measured results show that in the frequency band of 73.5GHz～74.5GHz,after cascading the linearized driving component,the output P1 dB of the final stage power amplifier is improved by 1dB～3dB,and the IMD3 is improved by 0.9dB～10.1dB.The linearization effect of the 3W-level high power solid state power amplifier has been realized.