| Translation: Phased array radars are moving towards exploring higher frequency bands,but solving problems such as weak penetration ability of high-frequency signals and short transmission distances requires support from RF front-end receiver systems with multichannel synthesis and high-precision amplitude-phase control.Additionally,as the number of communication terminals continues to increase,phased array systems must meet higher requirements for cost,integration,and power consumption.Due to the advantages of low power consumption,high integration,and low cost offered by silicon-based technology,it is widely applied in phased array systems.The main research contents and innovative achievements are divided into the following six parts:(1)The design direction of the phased array RF system is clarified by consulting the relevant literature of the phased array system and the module circuit in recent years.The phased array RF front-end receiving systems operating at 6-18 GHz and 27-32 GHz are proposed based on Si Ge Bi CMOS and CMOS processes.Perform performance index analysis and module index decomposition of the system,and verify the feasibility of the system and module indexes through system budget simulation.(2)The low noise amplifier performance determines the sensitivity of the receiver,and the bandwidth directly affects the beam scan width.Therefore,the emitter follower based Xband LNA is designed to reduce the constraints between gain loading and input matching performance.The measured results show a maximum gain of 20.1d B and a minimum noise of 2.8d B for 6-18 GHz.The Ka-band low-noise amplifier adopts transformer broadband matching and source-drain feedback technology to achieve an ultra-wideband LNA with flat gain response for 27-32 GHz.The maximum gain is 20.8d B,and the minimum noise is 4.4d B.(3)As the core module of phase control,the phase shift error of the phase shifter affects the beam scanning pointing error,the phase shift accuracy affects the phase resolution,and the additional attenuation also affects the stability of the phased array amplitude control.The Xband phase shifter adopts a sub-phase shifter array and a synthesizer double-vector synthesis structure to optimize the phase shifting accuracy and realize phase control.Simulation results show that the 360° five-bit phase shifting is achieved within the operating frequency range of 6-18 GHz.The Ka-band phase shifter optimizes additional attenuation based on an improved orthogonal generator and improves phase shifting accuracy through a simulated control vector synthesizer.Simulation results show that the phase shifter achieves six-bit phase shifting within the 27-32 GHz frequency range.(4)The attenuator is the core module of the amplitude control,and the attenuation accuracy and error affect the system sidelobe suppression ratio performance.The X-band attenuator adopts the current steering structure to realize four-bit attenuation control,adopts resistancecapacitance negative feedback technology to increase bandwidth,and introduces the d Blinear compensation structure to improve d B-linear control characteristics to optimize attenuation range and error.Simulation results show that this attenuator achieves four-bit attenuation of 22 d B within the 6-18 GHz frequency band.The Ka-band attenuator adopts an active-passive structure,where the active structure uses current extraction technology to control the equivalent transconductance for attenuation control and the additional phase shift is optimized using a phase compensation structure.The passive structure utilizes the π-type resistor attenuation and capacitance compensation structure to optimize the additional phase shift.Simulation results show that the attenuator achieves 6-bit attenuation in the frequency range of 27-32 GHz,and the attenuation range is 31.5d B.(5)As an important circuit module that affects the isolation of the transmission and reception link,this thesis designs an RF switch based on a novel triple-coupled transformer.The physical isolation between the two secondary windings ensures the isolation,and provides additional degrees of freedom to optimize the insertion loss.The RF switch is implemented and verified based on CMOS technology.The simulation results show that the RF switch achieves isolation better than 23 d B in the Ka frequency band,and the insertion loss is not higher than 2.5d B.(6)Utilizing the aforementioned module circuits as the foundation of the design,the phased array RF front-end receiving system is developed by integrating multiple modules and optimizing system matching.The X-band phased array RF receiver front-end realizes 360°five-phase shift and 22.5d B four-bit attenuation in the 6-18 GHz frequency range,and the root mean square phase shift error and attenuation error are less than 2.76° and 0.37 d B respectively.The channel power gain is 24.4d B.The Ka-band phased array RF receiver front-end achieves 360° six-phase shift and 31.5d B six-bit attenuation in the 27-32 GHz frequency range,and the root mean square phase shift error and root mean square attenuation error are less than 1.75° and 0.3d B respectively.The X-band and Ka-band phased array RF front-end receiving system constructed in this article has achieved all the design specifications.Compared with similar phased array RF front-end receiving systems,the proposed X-band and Ka-band RF front-end receiving systems have certain advantages. |
