Research On Key Technology Of Silicon-based Millimeter Wave Phase Shifter Based On Phased Array System

In last few years,phased array technology has achieved more and more great results in the current communication field.It is widely employed in communication satellites,missile attitude adjustment,weather monitoring,air control and other directions.The United States adopts multifunctional phased array radar to simultaneously realize aircraft surveillance.And the dual purpose of weather forecasting.And my country's demand for phased array radar is also increasing day by day,and its application direction is focused on the military field.As the pivotal module of the phased array,the phase shifter is mainly applied to adjust the signal transmission phase to form a difference with the reference phase,and then to control the beam direction.As a rising star,5G will be commercialized in the near future,and its prospects are very bright.The 5G frequency band is mainly divided into Sub6G and millimeter wave frequency bands.The advantages of large bandwidth,high speed,and low delay make related research in the millimeter wave field quickly become a hot spot.At the same time,the improvement of CMOS technology has made its characteristic frequency f_T reach hundreds of GHz,which can meet the relevant design requirements of current RF chips.The CMOS process is easy to integrate with digital,analog and other components,thus highlighting the advantages of low cost and high integration,and making the research on CMOS related technologies a trend and hot spot in the development of radio frequency chips.This article is based on the SMIC 55nm CMOS process to carry out related research on the Ka-band phase shifter,see below for details:1.For the purpose of weakening the impact of its parasitic parameters on the performance of the phase shifter,according to the inherent phase difference characteristics of the high and low pass structure,combined with the transistor switch model,a 6-bit digital phase shifter with an operating frequency of 32GHz?38GHz was designed and implemented.,Its phase shifting unit circuit is designed with a ?/T type and switch type structure,and the layout design is finally completed by optimizing the circuit structure and layout.The final test result is:S21>-25d B,RMS phase shift error<8°,standing wave at each port<2.2.Aiming at the shortcomings of the passive phase shifter of large area and large insertion loss,an active phase shifter that can be integrated in a multi-function chip is designed.The phase shifter consists of a passive balun,a quadrature signal generator,VGA,DAC and other circuits,the single-ended signal generates four relatively accurate reference phases through orthogonal transformation,and uses the DAC to control the variable gain amplifier,and synthesizes the differential signal of the corresponding quadrant based on the parallelogram rule,and generates it after passing through the balun again.Single-ended signal.The final test results show that the insertion loss is less than26d B in the frequency range of 32?38GHz,the RMS error is less than 6°,and the additional attenuation is less than±4.5d B.3.In view of the large additional attenuation of the phase shift and the inaccuracy of the quadrature reference phase in the previous active phase shifter test,two new structures are proposed:an amplitude modulation network based on switch control and a phase modulation network based on varactor diode control.It can realize amplitude tuning and phase tuning,and can improve its phase-shift RMS error and phase-shift additional attenuation index.The final simulation results show that the working frequency band is32GHz?38GHz,the insertion loss is less than 14d B,the RMS error is less than 2.5°,the phase shift additional attenuation is less than±0.6d B,and the standing wave of each port is less than 2.