Design Of Millimeter Wave Front-end For 5G Massive MIMO Communication

With the rapid development of mobile Internet technology and the Internet of Things technology,various new application scenarios have put forward more stringent requirements on the data transmission rate,network capacity,network delay and reliability of communication.Driven by the actual demand and technological development,the research and development of the new generation of 5G mobile communication systems grow rapidly.By using the millimeter wave frequency band,high capacity and high data transmission rate can be achieved for the 5G communication systems.Furthermore,the use of massive MIMO technology for spatial multiplexing can effectively improve the coverage and spectrum efficiency of 5G communication systems.This thesis focuses on the research on the millimeter wave front end for the 5G massive MIMO communication systems,finish the design of the millimeter wave front end transceiver and frequency source module.Firstly,based on the 5G millimeter wave candidate frequency band,the wideband RF transceiver operating from 24.25 GHz to 30 GHz is designed based on the the superheterodyne structure.Moreover,the scheme of frequency doubling and an external local oscillator is used to reduce the design difficulty of the frequency source.The IF frequency is 7.5 GHz and the channel bandwidth is 400 MHz.The design is verified by link simulation on the transceiver channel.And the RF filter and LO filter are designed based on substrate integrated waveguide and micrstrip line structure respectively.Finally,the transceiver front end is designed,fabricated and tested,the measured results indicate that the in-band gain flatness of the transmitter is less than 1.5d B and the in-band gain flatness of the receiver is less than 2d B.The EVM of transmitter with the 5G NR modulated signal in the 400 MHz bandwidth at 28 GHz is about-42.3d B,and the EVM of receiver with the5 G NR modulated signal in the 400 MHz bandwidth at 28 GHz is about-37.39 d B.The measured results show that the single channel millimeter wave front end transceiver has good performance.Besides,a wideband frequency source is designed based on the structure of two-stage PLL cascade with an output frequency range from 8.375 GHz to11.25 GHz.The first stage PLL locks the 10 MHz reference input signal to 100 MHz as the reference input for the subsequent PLL in order to obtain better frequency stability and phase noise.The second stage frequency synthesizer uses a PLL chip with integrated VCO to achieve a broadband LO signal output range from 8.375 GHz to 11.25 GHz.The output power of the frequency synthesizer is above 0d Bm.The measured phase noise of the frequency source module are about-95.05 d Bc/Hz@1KHz?-102.26 d Bc/Hz@10KHz?-104.77 d Bc/Hz@100KHz?-115.69 d Bc/Hz@1MHz.In order to support the application of massive MIMO communication systems,power distribution network for LO signal is designed and tested,including power divider,filter and amplifier.