Research On Amplitude And Phase Control Circuits In CMOS Millimeter-Wave Phased Array Chips

In recent years,the millimeter-wave communication technology has experienced rapid de-velopment and has been widely adopted in systems such as the high-throughput satellite com-munication and the 5th generation mobile communication systems.As the key enabling tech-nology of millimeter-wave communication,the millimeter-wave phased array can enhance the gain of the communication link,provide flexible signal coverage and suppress interferences.The implementation of low-cost,low-power-consumption and high-integration phased-array chip is the prerequisite for large-scale application of millimeter-wave phased array.Based on the requirements of high-performance,low-cost and low-power-consumption millimeter-wave phased-array chips,this work focuses on the research of the amplitude and phase control cir-cuits,and proposes the analysis theories and design methods to achieve high-precision,low-cost and low-power-consumption amplitude and phase control designs.The proposed chips are fab-ricated in CMOS technology and measured on the probe station.The research supports the development of millimeter-wave phased-array systems.Firstly,the transmission characteristics of phased array in millimeter-wave band are stud-ied.A quantitative analysis of the beam squint effect on communication quality has been carried out,where the error vector magnitudes for different array sizes,beam directions and symbol rates are calculated,revealing that the phased array can provide reliable communication quality for the system using a small relative bandwidth.Based on millimeter-wave phased-array sys-tem requirements,the key parameters of the amplitude and phase control circuits are sorted out,which guides the circuit optimizations.Aiming at the low-power-consumption and high-precision phase control requirements,based on the reflective-type phase shifter,analysis theories and design methods are studied.The geometric analysis method is proposed to analyze the reflection loads.The phase shift range and phase shift loss are directly related to the trajectory of the load impedance in the com-plex plane.Three classical reflective loads are analyzed with the geometric analysis method,and their phase shifting characteristics and limitations are discussed.The triple-resonating load technique is proposed to enhance the phase shift range.The fact that the impedance of the triple-resonating load has an analytical expression similar to a circle in the complex plane is proven,which provides theoretical support for minimizing the amplitude error.The dual volt-age control method is applied to the triple-resonating load,which further reduces the phase shift amplitude error and improves the operation bandwidth.Based on 65 nm CMOS technology,a Ka-band reflective-type phase shifter is designed and fabricated,which achieves zero DC power consumption,±0.2dB amplitude error and full 360°continuous phase shift range.Besides,it supports both single-voltage and dual-voltage control modes,and only occupies a compact chip area.Aiming at the low-power-consumption,wideband and high-precision phase control re-quirements,based on the passive vector-modulated phase shifter,analysis theories and design methods are studied.The transmission and reflection characteristics of the X-type attenuator are derived.The amplitude tuning characteristics with PVT variations are modeled,which pro-vides theoretical support for minimizing the amplitude error.The transmission and reflection characteristics of current combining and power combining structures are derived,which guides the design of combining structures in passive vector-modulated phase shifters.The dual-bit control method is proposed to improve the phase-shifting accuracy and bandwidth.Based on40 nm CMOS technology,an E-band passive vector-modulated phase shifter is designed and fabricated,which achieves zero DC power consumption,70-90 GHz broad bandwidth,<2.4°RMS phase error and <0.6 dB amplitude error simultaneously.Aiming at the low-power-consumption,wideband and high-precision amplitude control requirements,based on the switched-type attenuator,the analysis theories and design methods are studied.The transmission and reflection parameters of the simplified-T,T- and Π-type at-tenuation structures in reference and attenuation states are derived.A cyclic-feedback-based calculation process is proposed to calculate the resistance values,which reduces calculation complexity and provides good accuracy.The reasons of performance limitations at high fre-quencies are analyzed.The amplitude and phase responses of the compensated attenuation units using different transistor sizes,attenuation levels and attenuation structures are calcu-lated,which guides the optimization of the capacitive compensation technique.Based on 65 nm CMOS technology,a switched-type attenuator is designed and fabricated,which achieves zero DC power consumption,DC-50 GHz ultra-broad bandwidth and <0.25 dB RMS amplitude error.