Design And Development Of 5G Terminal RF Switch And Antenna Tuner

With the rapid development of integrated circuits and wireless communication technologies,mobile phones have become a necessity in people’s lives.After entering the 5G era,due to the increasing requirements of users for the speed and stability of data connection,the number of phone antennas increases when the volume decreases,which affect the antenna performance.Antenna tuning is the mainstream method to solve this problem.The RF switch is the core component of antenna tuner,therefore the design of the RF switch and antenna tuner is deeply studied in this paper.Firstly,this paper analyzes the advantages of SOI process,and an antenna tuner suitable for 5G mobile terminal is designed based on 180nm SOI process.The tuning network is composed of SP3T RF switch and 5bit digital programmable capacitor array in parallel.In order to accurately simulate and test the Ron and Coff of the switch,the on and off models of the RF switch are analyzed,and the calculation formulas of Ron and Coff are proposed.The transistor in the RF switch adopts a symmetrical double-bias structure,in order to improve the on-off performance of the switch,positive and negative charge pump are used,and finally+2.7V and a-1.8V are obtained.In order to improve the tuning range,a capacitor array with a binary-weighted parallel structure based on RF switche is designed,which has high tuning ratio and capacitor adjustment accuracy.In addition,in order to improve the integration level,the mixed digital-analog control circuit including MIPI circuit,LDO circuit,reset circuit and other modules are integrated on the same die with the RF circuit.Finally,this paper analyzes the layout design of the chip,and extracts the parasitic parameters of the layout for post-simulation.The test results of the antenna tuner chip in this paper are as follows:capacitor of capacitor array can be digitally programmed from 0.3 pF to 3.4pF in 0.1 pF steps and shows a maximum quality factor of 36 at 1GHz.For the SP3T switch,the DC Ron is 1Ω,Coff is 180fF,insert loss is 0.86dB,isolation is 17dB at 2.7GHz and the second harmonic and third harmonic are-62dBm and-57dBm when driven by 35dBm signal.The test results show that the performance of the antenna tuner meet the design goals,and can be applied to 5G mobile terminals,which plays a certain role in promoting the research of antenna tuners.