Development Of 5G HTS Receiver Front-end

With the rapid development of the fifth generation mobile communication technol-ogy and its commercial application in the frequency band below 6GHz,higher require-ments are put forward for the transmission rate,noise coefficient,sensitivity and delay of the receiver.Due to the shortage of spectrum resources and serious interference below6GHz,it is of great significance to develop a receiver front-end with low delay,low noise coefficient and high sensitivity.In this thesis,a high-temperature superconducting?HTS?thin-film material is used to develop a 5G HTS receiver front-end,which works in two discrete 5G frequency bands obtained by China Mobile.The receiving front-end adopts the cascade structure of high temperature superconducting filter?HTSBPF?and low temperature low noise amplifier?LTLNA?,which not only realizes low noise coefficient,high sensitivity,but also has the performance of anti-interference and strong out of band suppression.The core component HTSBPF adopts branch-loaded SIR resonant structure and cross-coupling structure.Through theoretical analysis and electromagnetic simulation of the resonant structure,this article synthesizes the relationship curve between resonator size,coupling coefficient and external quality factor to guide the design of the filter.After simulation and optimization,a double-passband filter with linear phase characteristics is designed and implemented on the superconducting diaphragm of LaAlO₃substrate.Its insertion loss is only 0.3dB,and the deepest out-of-band suppression can reach 80dB,the group delay in the two passbands is less than±6ns.The bandwidth and frequency of the two passbands are independently adjustable.Compared with the ordinary filter,it not only reduces the size,but also moves the parasitic passband beyond the center frequency3 times.Another core component,LTLNA,is designed and implemented through MMIC chip selection,static operating point analysis,stability analysis,circuit simulation,layout simulation,processing and assembly and other steps.The low noise can provide a gain of more than 20dB in the required working band of 2?5GHz,the in-band fluctuation is±0.5dB,and the noise is only 0.8dB,which meets the needs of the system.By combining the designed HTS filter and the LNA,5G HTS receiver front-end can be obtained.In the vacuum environment,at the temperature of 75K,the test results show that the target of the HTS receiver front-end is as follows:The center frequency point of passband I is 2.595GHz,the bandwidth is 160MHz,the center frequency point of passband II is 4.85GHz,the bandwidth is 100MHz,the noise coefficient NF in passband is less than 1.4dB,the out of band suppression is better than 50dB,the intra band group delay fluctuation is less than±10ns,which meets the design goal.