Development Of Multi-channel Frequency Synthesizer For 5G Wireless Communication System

Frequency synthesizer is one of the key components in modern wireless communication systems.The quality of transmitted and received signals is directly affected by the quality of local oscillator(LO)signals.Thus,the LO signal has a significant impact on the performance of entire communication systems.Based on the 5G Massive MIMO digital multibeam array system and 5G millimeter wave(MMW)phased array system,this thesis conducts research on high-performance frequency synthesizers.The main work is as follows:1)The 5G Massive MIMO communication system has much more critical requirments for the synchronization of frequency?time and phase.Therefore,more accurate frequency synthesizers are in great demand.In this thesis,a phase-locked loop(PLL)frequency synthesizer and the power distribution module are developed for the 5G Massive MIMO digital multibeam array system.The PLL frequency synthesizer provides a common LO signal for 64 transceivers,which guarantees the channel uniformity of coherent sytems and makes it convenient for system one-time calibration and digital beamforming.The test results show that the PLL frequency synthesizer can generate siganls from 850 MHz to 12 GHz with a very fine frequency resolution.After the output 3.875 GHz signal which is aimed to be the LO signal for the 5G system in 3.5GHz goes through the 8-way power distribution module,the amplitudes of the output signals are all about 5d Bm.And there is only one spur signal within 30 MHz frequency offset,and the spur level is below-77 d Bc.The mearsured phase noise of the 3.875 GHz signal are-102.84 d Bc/Hz@1k Hz,-107.23 d Bc/Hz@10k Hz,-106.38 d Bc/Hz@100k Hz and-137.39 d Bc/Hz@1MHz respectively.The far-away phase noise is below-155 d Bc/Hz,and the harmonic suppression is greater than 60 d B.The test results indicate that the PLL frequency synthesizer has a good performance and can meet the requirements of the 5G Massive MIMO digital multibeam array system.2)Based on the requirements of performance specification in MMW phased array transceiver system,a 16-channel direct digital frequency synthesizer(DDS)is developed for intermediate frequency phase shifting.The DDS frequency synthesizer can provide high precision amplitude and phase control.The test results show that the output 3.7GHz signals of 16 channels are all about 6d Bm after amplitude calibration.The mearsured phase noise of the 3.7GHz signal are-89.25 d Bc/Hz@1k Hz,-115.8d Bc/Hz@10k Hz,-121.45 d Bc/Hz @100k Hz and-133.83 d Bc/Hz@1MHz respectively.The far-away phase noise is below-145 d Bc/Hz and the harmonic suppression is greater than 45 d B.The 16 channels' phase control accuracy is within 1°.Furthermore,I did data processing of the sampled signal with MATLAB software to abtain more accurate amplitude and phase calibration result.The shortterm and longterm stability of the DDS signal is also analyzed.At last,using the the DDS frequency synthesizer for LO phase shifting in MMW phased array system is introduced.The receiving phased array beam scanning results are tested in microwave anechoic chamber when the scan angle is 0°?±3°and ±5°.