Research On RF Module For 5G Millimeter-wave Multi-beam Array

With the continuous development of mobile communication technology,higher requirements are put forward for high data rate,low latency and flexible connection.The millimeter-wave frequency band with a large number of available spectrum resources has become a research hotspot in 5G communication technology.The radio frequency(RF)module in the millimeter wave multi-beam array system needs to realize the characteristics of high frequency,broadband and multi-channels,while maintaining good performance and low cost.This paper focuses on the research of 5G millimeter wave multi-beam array RF module,and respectively completes the design of low-power RF module and high-performance RF module.This paper firstly introduces the structure scheme of the multi-beam array system,and designs the local oscillator(LO)module applied to the multi-beam array system.It uses a twostage phase-locked loop cascade structure to output broadband LO signal with frequency range of 10.65GHz-12.05 GHz.This study also designs LO signal chain,including LO filter,power divider and amplifier.The LO module test in the operating frequency band shows that the output power is higher than-10 d Bm,the suppression of the second and third harmonics is more than40 d Bc,and the phase noise is about-95 d Bc/Hz@1k Hz,-106 d Bc/Hz@10k Hz,-107 d Bc/Hz@100k Hz,-120 d Bc/Hz@1MHz.This paper designs a four-channel low-power compact RF module that works in the 27-29.5GHz frequency band which integrates the LO module and can share the common transceiver channel.The rationality of the RF module scheme is verified through architecture analysis and link simulation.Besides,RF bandpass filter is designed by using the substrate integrated waveguide(SIW)dual-coupling window structure and the cross-coupling structure.Tests on the RF module show that the power consumption of the four-channel RF module is about 6.84 W,the performance of each transceiver channel is consistent,gain flatness is less than 2d B,out-of-band spurious suppression and linearity performance well.When the transceiver channel 1 works at 28 GHz,the measured transmission error vector magnitude(EVM)are about 2.60% and 2.49%,respectively with the symbol rate of 100 Msps for 64 QAM and 256 QAM modulation,while the receiving EVM are about 1.67% and 1.54%.All performances have reached expectations.Taking into account the limitations of low-power RF modules in terms of linearity and gain adjustable range,the paper also designed a high-performance RF module that works at24.75-27.5GHz.In the design,spurious simulation and indicator budget were carried out,the device selection of the mixers and the intermediate frequency(IF)gain control part was completed,and the design of the intermediate frequency filter was completed by using the microstrip folded ladder impedance resonator(FSIR)structure.The test results show that single channel RF module power consumption is about 5.28 W,the transmit channel gain flatness is less than 2.5d B,the output 1d B compression point and third-order intercept point are 9.4d Bm and 19.426 d Bm respectively,ACPR is lower than-44 d Bc;the receive channel gain flatness is less than 3d B,the output 1d B compression point and third-order intercept point are-2.3d Bm and 7.68 d Bm respectively,image rejection is higher than 55 d Bc.When the module works at25 GHz,the transmit EVM of the transceiver channel under 100 Mbps symbol rate is about1.48%,1.39%,1.33%,1.37% and receive EVM is about 1.69%,1.92%,1.96%,1.96% under QPSK,16 QAM,64QAM and 256 QAM modulation respectively.The indicators meet the performance requirements of the multi-beam array system for the RF module.