Key Techniques For Millimeter-wave/Terahertz Solid-state Power Combining

Millimeter-wave and terahertz frequency band is the focus of next-generation communications.Transmitting power is a significant figure in a terahertz system,and the power level determines the operating distance of the system.Solid-state power devices in the millimeter-wave terahertz band have made remarkable progress in recent years,which has promoted the development of domestic terahertz technology.The output power of a single power device is is insufficient to meet the system requirements.Therefore,research on the involved theory and techniques of millimeter-wave and terahertz solid-state power combining are of great significance for engineering。W-and G-band power combining technology based on in-house Ga N power devices was re-searched in this work,including circular waveguide radial combining technology,silicon microm-achined waveguide combining technology,and engineering technology of millimeter-wave and te-rahertz solid-state power amplifier（SSPA）.A W-band 100W SSPA and G-band 1W SSPA were developed.The main work in this dissertation is as follows:1.The transmission modes of the circular waveguide were analyzed and the power combining solution excited by the high-order modes of the circular waveguide is proposed.A TE₀₁ mode and a TM₀₁ mode radial combiner are developed.The W band muti-way radial combining solutions by high order mode excitation shows the advantages of high efficiency,simple pro-cessing and compact sizes.Specifically,the electromagnetic field distribution of the TE₀₁ and TM₀₁ modes in the circular waveguide is analyzed and corresponding radial combiners are respectively realized.A 16-way TE₀₁ mode radial combiner and an 8-way TM₀₁mode radial combiner are designed and fabricated.The final test results of the two circular waveguide radial combiners show the combining efficiency of 92%and 80%.2.Based on a low-loss waveguide sealing structure and EBG pins cavity resonance suppression structure,the W band packaging technology of MMICs is proposed.Specifically,the chip packaging and high-efficiency combining are studied,for the development of W-band high-power solid-state combining amplifier.As the W-band power amplifier module with an out-put of rectangle waveguide,a W-band low-loss waveguide sealing structure is realized by a packaging structure integrated the microstrip probe.A cavity resonance suppression method based on the EBG pins structure is proposed,and a W-band packaged power amplifier mod-ule is realized.Based on the developed power amplifier module,a 15Watt power amplifier module is fabricated,using a miniaturized 8-way waveguide combiner.Under the achieve-ments of W-band solid-state power amplifier engineering technology,the output power of100 Watt was finally presented in the W-band.3.A silicon micromachined waveguide combineing technique is proposed.Be the first to achieve the silicon rectangle waveguide combined power amplifiers and the silicon circular waveguide radial combined power amplifier.A nano-level precision waveguide processing is achieved by the semiconductor technology,and a high-efficiency power combining solu-tion is provided for the millimeter wave and terahertz frequency band.With the characteris-tics of the silicon micromaching process,an H-T combiner and a two-way parallel waveguide combiner were designed,and a silicon H-T combiner and a silicon four-way waveguide com-biner were fabricated to obtain a higher combining efficiency.Two silicon combined power amplifier modules have been realized by integrating silicon combiners,microstrip probes,and Ga N power MMICs.The test result shows the 2-way silicon combined power amplifier module has achieved an output power of 4.25W,the PAE is 14.7%,and the typical combining efficiency is greater than 92%;the 4-way silicon combined power amplifier module has achieved 8.05W,the PAE is 15.05%,and the typical combining efficiency is greater than88%.Based on circular waveguide TM₀₁ mode excitation,a compact 8-way silicon radial combiner is realized by the stacking of two layers of silicon wafers,deep silicon etching,and gold-gold bonding technique.And a TM₀₁ mode converter is designed using the silicon H-T combiner.Then,a W-band silicon radial combined power amplifier was developed.The tesed output power is higher than 24.7W in the frequency range of 92–96 GHz,the peak power reaches 31W,the peak PAE reaches 13.2%.Compared with the traditonal radial PA modules,the volume was reduced by more than 75%.These developed techniques are provides a high integration,miniaturized SSPA solution for millimeter wave systems.4.Key Techniques breakthroughs of G band solid-state power combining is accomplished and a G band 1 Watt SSPA is achieved by the in-house Ga N power devices and high efficiency combiner.The transmission loss of the G-band waveguide is calculated and analyzed and the design criteria of the terahertz power combiner is determined.An E-plane T-junction com-biner and a new H-plane T-junction combiner based on the overmode waveguide are pro-posed,as well as a 4-way raidal combiner are proposed,and all these combiners show good combineing efficiency.According to the assembly characteristics of terahertz chips,a com-pensation technology by a low-pass filter structure is proposed,which absorbs the disconti-nuity caused by gold wire bonding.And then e a G-band 2-way combined PA module is fabricated.Under further power combining,a typical output power of 1W was finally ob-tained at the G-band,which broke through the technical bottleneck of the domestic G band high-power solid-state power amplifier.