Design Of 6~18GHz Wideband Active Phase Shifter In SiGe BiCMOS Technology

With the increasing demand for radar,phased array systems have been widely used in military and civilian applications in China for their extremely fast response speed,strong anti-interference ability and multi-target tracking capabilities.The phase shifter is the core module in the phased array system,and its performance determines the performance of the entire phased array system.Conventional passive phase shifters affect the performance of phased array systems seriously due to their large chip area,high phase shift error,narrow operating bandwidth,and high loss.At the same time,with the maturity of silicon-based processes,active phase shifters using SiGe BiCMOS technology have solved the shortcomings of traditional passive phase shifters in recent years,such as low integration and high loss.It accelerates the application and development of phased array systems using in X and Ku bands.Therefore,broadband active phase shifters based on SiGe BiCMOS technology have become the next research hotspot.This paper designs a 6-18 GHz wideband active phase shifter based on 0.13μm SiGe BiCMOS process.The wideband active phase shifter adopts the structure of the vector modulation active phase shifter.Specific modules include an input balun,a wideband differential amplifier,a quadrature signal generator,a vector modulator,a digital-to-analog converter（DAC）and a wideband loss-compensation amplifier.The input balun adopts the structure of the passive Marchand balun.The quadrature signal generator is composed of a wideband differential amplifier and a poly-phase filter.The vector modulator includes two VGAs based on Gilbert cells,and the gain of VGAs is controlled by the DAC.This paper has made some improvements and innovations on the structure of the traditional active phase shifter,which inserts a wideband differential amplifier between the passive Marchand balun and the poly-phase filter.It performs the function of input-output impedance matching,providing a 50Ωload to the pre-stage passive Marchand balun and a 50Ωsource impedance to the post-stage poly-phase filter.The advantage of this structure is that it reduces the phase error and amplitude error of the output of the passive Marchand balun and poly-phase filter,and has made great improvements and breakthroughs compared with the traditional structure.Under the TT process corner and the common temperature,the result of the EM simulation of this active phase shifter shows a 0.51-1.14°RMS phase error and a 0.28-0.4dB RMS gain error for 64 phase states in the 6-18GHz range.The simulation result also shows a 9.2-11.66dB power gain with the S₁₁ less than-12.3dB and the S₂₂ less than-11.4dB in the 6-18GHz range.Meanwhile,the phase shifter achieves an input P1dB more than 1 dBm in the 6-18 GHz range for 64 phase state.The core area of the phase shifter is 2.46 mm×1.38mm,with a total current consumption of 33.7 mA from a 3.3V supply voltage.The wideband active phase shifter designed in this paper has high phase shift precision,small phase shift error,wide bandwidth and high linearity.It meets the requirements of indicators and can be used in the phased array radar.