Research On Key Technologies Of High-Resolution In-Tegrated Phase Shifters For RF/mm-Wave Phased-Array Systems

Phased arrays have the advantages of long transmission distance,high sensitivity,anti-interference,and have been an indispensable implementation technology in high-data-rate wireless communications,radar and imaging systems.With the increasing demand for applications such as 5G communications and automotive radars,low-cost high-performance phased-array systems have become a research hot point.Phased array modules and system chips based on silicon-based/III-V process are emerging in large numbers.The high data rate for communication applications and the high resolution for radar and imaging applications are main performance focuses of phased array integrated systems.Phase shifters（PSs）as the key blocks of phased array systems,its performance greatly determines the beamforming quality and beam-scanning accuracy of phased array systems,and further influences the data rate of communication applications and the imaging resolution of radar applications.Therefore,the performance increasing of PSs is an important issue of phased array systems.For phased array applications such as high date-rate communication and high-precision radar,this dissertation has made an in-depth study on the RF/millimeter-wave PS.The high-precision and high-resolution implementation of passive and active PSs,which are fabricated in different process and operating in different frequency range,are studied.The main contents and innovations of the dissertation are summarized as follows:（1）For the passive PSs,which are suitable for high linearity and low power consumption phased array applications,in order to overcome the design limitations of passive PSs in phase resolution and phase accuracy due to parasitic effects and other factors,this dissertation proposed a compensation T-type switch-type phase shift unit,a system-level amplitude compensation design method,and a reflection-type phase shifting technology based on transformer coupling to improve the phase resolution and accuracy of the passive PSs.Based on these,the phase shifters have been designed and verified:a.For the processes with low insertion loss transistor switches,such as III-V technologies,in order to improve the phase resolution and accuracy of the PS,through the analysis of the transistor switching characteristics,a T-type switch-type phase shifting cell with amplitude and phase compensation is proposed to overcome the influence of the transistor turn-off capacitance on the accuracy and bandwidth of the traditional T-type phase shift cell.At the same time,by analyzing the amplitude characteristics of phase-shifting units of different structures,a system-level amplitude compensation design method is proposed.Based on above technologies,A 2.4-4 GHz wideband 7-bit switch-type phase shifter（STPS）based on Ga As process with a switch driver is design.And the implemented 7-bit STPS has a 3.1°RMS phase error and a0.34 d B RMS amplitude error,which has obvious performance advantages compared with the similar researches and products.b.For the processes with high insertion loss transistor switches,such as silicon-based technologies,it is difficult to improve the phase resolution and accuracy of passive PSs by increasing the number of cascaded switch-type phase shifting cells.And in order to overcome the decrease of phase accuracy caused by the increased parasitic effects at high frequency,a high-precision reflection-type phase shifting load structure based on transformer impedance conversion is proposed.And a 30-36 GHz passive hybrid phase shifter is designed.The proof-of-concept prototype achieves a 2.8°phase resolution,and the RMS phase error of the PS is 0.69-1.1°at 30-34 GHz.（2）For active phase shifters,which are suitable for high gain and low noise figure phased array applications,in order to improve the phase resolution and phase control efficiency of active PSs,the nonlinear DAC amplitude compensation technology and a simplified single-ended IQ vector modulator phase shifter（VMPS）structure are proposed.Based on these,two mm-wave active PSs are designed and taped out for verification:a.For the amplitude-sensitive application with mm-wave active PSs,in order to solve the problem of improving the phase resolution and accuracy over a wide frequency range.This dissertation proposed a gain compensation control technology based on the nonlinear digital-to-analog converter by analyzing the amplitude and phase of the IQ vector modulator signal.This technology can reshape the change trend of the variable gain amplifier in the phase shifter with the gain of the control word,thereby improving the phase shift accuracy of the phase shifter.Base on this technology,a 24-30 GHz VMPS for 5G communication is proposed.The VMPS also adopts a low insertion loss hybrid coupler and the emitter negative feedback technology.The realized chip achieves a 6-bit phase resolution,and the RMS phase error less than 2°at24-30 GHz.The gain of the VMPS is 1.2-2.3 d B,and the IP_{1d B} is more than-3 d Bm.b.For the source frequency doubling phased array architecture,which requires higher phase resolution,this dissertation proposed a simplified single-end IQ VMPS structure.This structure also contains an IQ generator with same side output terminals,and realizes high-resolution phase shifting with a simple circuit structure.A 33-37 GHz high resolution VMPS is design based on the proposed structure.The PS achieve 90°phase shifting range with a 0.7°phase step.The measured results show that the RMS phase error is 0.15-0.36°at operating frequency range.The power consumption is 18mW,and the core area of the chip is 0.21 mm².