Study On Structures And Circuit Design Of Dual-Band Monolithic Microwave Phase Shifters With Independent Phase Shifts

Phased array systems are foundation of modern communication massive MIMO technology.Phase shifters are key building blocks in phased array systems.Traditional single-band phase shifters can only provide phase shifts over a successive frequency range.With the rapid development of emerging smart electronics,such as 5G communication and automatic driving,phased array systems that independently support two frequency bands are in great need.Double single-band phase shifters deployed in one multi-band phased array can solve the problem of frequency bands coverage and independent control,but the complexity,cost and size of the system will grow.Therefore,it is necessary to study the structures and circuit design of phase shifters that can independently operate in two frequency bands.Based on the control methods,phase shifters can be divided into analog type and digital type.Analog phase shifters with continuous phase change are suitable for applications which require precise phase shift.While digital phase shifters are more popular due to its compatibility with computer automatic control.Current dual-band phase shifters fail to provide independent phase shifts.They usually face the limitation that high band phase shifts can not be smaller than low band phase shifts,which limits their application diversity.In this dissertation,structures and circuit design of dual-band monolithic microwave phase shifters with independent phase shifts are deeply researched.The contents can be divided into three parts as follows:(1)To solve the problem that analog dual-band phase shifter can not provide independent phase shifts,a C-/Ku-band dual-band tunable concurrent passive phase shifter monolithic microwave integrated circuit utilizing a two-stage dual-branch phase tuning network topology for dual-beam satcom applications is proposed.The designed phase shifter with two independent phase tuning bands operates at 5.9 GHz and 16 GHz.The dual-band phase shifter is fabricated in a 0.25μm GaAs process and occupies a small chip area of 0.92mm×1.06 mm.Measurement results show that transmission phase in the two frequency bands can be tuned concurrently.Phase tuning range is greater than105° in either band.The proposed phase shifter is employed in a four-element dual-band phased array network.The phased array is able to independently tilt its main beam toward-20°～+20° in either band.(2)To solve the problem that digital dual-band phase shifter can not provide independent phase shifts,C-/K-band dual-band independent controllable fixed phase shifter monolithic microwave integrated circuits based on all-pass networks for land mobile communication applications are proposed.The designed 90° and 180° phase shifters are able to operate on low-band mode,high-band mode,and concurrent dual-band mode.The low-band and high-band are 1ocated in 4.7～5.5 GHz and 24～27GHz respectively.A phase compensation scheme is proposed to eliminate phase errors in multi-mode operation.The dual-band phase shifters were fabricated in a 0.15 um GaAs pHEMT process and occupy a chip area of 2.16mm×1.24 mm and 2.35mm×1.24 mm.A 2-bit dual-band digital controlled phase shifter is further developed based on the fixed phase shifters.The digital phase shifter achieves RMS phase errors of 4.6° and 4.3° in low band and high band,respectively.The proposed phase shifters support the sub-6GHz and n258 mm-wave band of 5G communication.(3)To solve the problem that performances deviation caused by dual-band interacts of concurrent dual-band phase shifters,a K-/Ka-band active phase shifter utilizing a frequency-reconfigurable vector-summing topology for 5G mm-wave applications is proposed.A band-switchable I/Q signal generator followed by band-switchable single-to-differential variable gain amplifiers is employed to build the phase shifter.The designed phase shifter can be switched to operate over 24-30 GHz band or 35-41 GHz band.The phase shifter,fabricated in 90 nm CMOS technology,provides 360° of phase shifting range in both frequency bands while consuming only 17.6 m W of power and0.75mm×0.45 mm of chip area.Measurement results show that the phase shifter’s RMS phase errors for 32 phase states are less than 4° and 5.1° over 24～30 GHz band or35～41 GHz band,respectively.RMS amplitude errors of the phase shifter for 32 measured phase states are less than 0.6 d B and 0.35 d B over the lower and higher operation bands,respectively.