Design Of The Q-band High-speed Broadband Transceiver RF Module

5th Generation Mobile Communication(5G)is a new generation mobile communication system developed to meet the explosive growth of data traffic and the requirements of complex application scenarios.At present,the frequency spectrum of the low frequency band is quite crowded,but the millimeter wave frequency band has abundant available spectrum resources which can be used to meet the high transmission rate requirements of 5G mobile communications.Therefore,millimeter wave mobile communications are receiving widespread attention and research in the industry.This paper has developed a Q-band high-speed broadband transceiver RF module,using a superheterodyne structure,its working RF frequency is 40.5-43.5GHz,and the intermediate frequency is 5.8GHz.It mainly includes three parts: transmitting link,receiving link and LO frequency multiplier circuit.The transmitting link up-converts the 5.8GHz intermediate frequency signal to the radio frequency,the receiving link down-converts the received radio frequency signal to the intermediate frequency,and the local oscillator frequency multiplier circuit is used to provide sufficient power for the transmitting and receiving link.In order to suppress out-of-band spurious signals,a triple-mode filter was developed using a substrate integrated waveguide(SIW)to suppress the local oscillator leakage and spurious signals of the transmission link,a source-load coupled four-cavity filter was developed for suppression of spurious signals in the receiving link and designed a four-cavity filter in LO frequency multiplier circuit.What's more,a coupler is designed using SIW,and a power divider is designed using microstrip structure.The actual measurement results show that the transmission link gain is about 12.5d B in the RF frequency range of 40.5-43.5GHz,and the channel gain flatness is 2d B.The modulation signals of 16 QAM and 64 QAM with a bandwidth of 400 MHz were used to perform EVM test on the transmission link,and EVM was better than 2.26% and 2.21%,respectively.The flatness and output spectrum of the receiving link channel are tested,the result shows that within each500 MHz channel bandwidth,the flatness is less than 1d B.The Q-band transceiver module and power amplifier are combined to form an envelope tracking(ET)amplifier test platform,and combined with digital predistortion(DPD)technology for testing,the EVM of the ET power amplifier is 0.8%,the ACLR is improved from-36.8/-37.9d Bc to-50.9/-48.8d Bc,and relative efficiency increased by up to 50%.