Research On Miniaturized Rf Transmitter For Next Generation Wireless Communication

The requirement of the next generation communication business is faster data rate and larger capacity.The current 5G spectrum includes two frequency ranges:FR1:Sub-6GHz band and FR2:mm Wave band.However,in the Sub-6G band,few wide continuous blank bands are available,and in the mm Wave band,although there are plenty of frequency resource,it is difficult to balance between the transmission loss and communication capacity,between the performance of key components and system costs.One of the best ways to the requirement is using wider bandwidth in a new frequency band near the 6GHz.At present,there is a large amount of blank spectrum in the 6-7GHz frequency band,which can balance between the larger communication capacity and the transmission loss.Therefore,this frequency band may become one of the new Gold Band for the next generation wireless communication.At the 2019 World Radiocommunication Conference,representatives from China promoted the new frequency band 5925-7125 MHz as the topic of the next WRC 2023.However,communication equipment in the 6-7GHz band also has many difficulties to further study currently.The main difficulty is that the most highly integrated RF components available do not have good performance beyond the 6GHz band and the size of the RF transceiver is too large for missive MIMO application.In order to solve the fundamental technical difficulties,this thesis presents research on miniaturized transmitters for next generation wireless communications in the 6-7GHz frequency band.To meet the demand for both communication capacity and coverage in next generation wireless communication,a good performance multi-channel RF transmitter is developed.The transmitter works in the 6.2-6.6GHz frequency band and the signal bandwidth is 400MHz.And the linear output power is greater than 34d Bm.The whole system also includes up-conversion module,RF power amplifier module,four-channel high-power low-phase noise local oscillator source module,power management module and digital control module.The transmitter uses the LO in the up-side frequency,which greatly reduces the risk of combined harmonics and spurious components falling within the operation band.Through the IF gain control module,the transmitter can obtain a larger dynamic range of the output power.By optimizing device placement and channel-to-channel layout,the final designed transmitter has an area of only17×8.3cm~2,which fulfills the requirement of miniaturization.The measured results show that the transmitter has good performance.The gain fluctuation of the transmitter is less than 1.4d B within the 400MHz working bandwidth.The transmitter output 1d B compression point is greater than 34d Bm.And the output 3rd order intercept point is 43 d Bm.The adjacent channel power ratio of 400MHz 5G NR signal is less than-45d Bc.Within the transmitter linear output power,the transmit EVM under 100Mbps symbol rate is about 1.48%,1.39%,1.33%,1.37%under QPSK,16QAM,64QAM and 256QAM modulation respectively,and the EVM degradation of 400MHz 5G NR signal is only 0.76%.The OTA communication performance of the transceiver system is very good as well.The measured results of the four-channel high-power low-phase-noise local oscillator show that:The output power of the local oscillator is up to 17 d Bm at 8.2 GHz,which can provide better linearity for the passive mixer of the transmitter and reduce the generation of harmonics.The suppression degree of the local oscillator at the second harmonic of 8.2 GHz is about 54d Bc,which can effectively reduce the power of harmonics;The integrated phase noise of the local oscillator source is only-51.7d Bc,which can reduce the degradation of transmit EVM.