Research Of A Broadband High-Precision 39 GHZ Phase Shifter

With the development of the society,mobile communication is playing a more and more important role in our daily life.With the demand for higher data rate,new bandwidth available for mobile communication needs to be expanded.Thus mm-wave frequency band(e.g.39GHz)has been included in the 5G spectrum.To improve the performance(e.g.the coverage)of mmwave communication system,phased array beamforming is required.Due to the indispensability of the phase shifter used in the phased array,the research related to the phase shifter is important.Phase shifter is a module in the phased array used for altering the phase of the signal.By setting specific phase of the signal in different channels,the transceiver can acquire large transmitting or receiving power in a certain direction by combining the signals together.A 6-bit differential switched-network phase shifter is introduced in this paper,which is based on65-nm CMOS with a tuning range of 360 degree.The phase shifter is comprised of 6 modules which is constructed by LC network.By tuning the voltage,the phase of the signal passing the phase shifter will be change.The module of 180°phase shift is obtained by swapping the differential signals,and other degrees are realized mainly by the switchover between by-pass and low-pass network.They result of simulation shows that both the input and output port of the module are well matched and can keep a constant phase shift in wideband.To enhance the suppression of noise,a differential structure is adpoted.Considering the demand of the system application,a scheme of 5-bit,180 degree tuning range phase shifter is adopted.And the following process such as tape out and testing is accomplished.The testing result introduces that the RMS phase error in the working band of36-43 GHz is less than 3°.And the average insertion loss is less than 10 d B and loss variation is less than 3d B(RMS loss variation is less than 1d B)in this band.Moreover,the return loss at input and output port is both less than-10 d B.The maximum value of insertion loss,9 d B,occurs at 43 GHz and the range of the insertion loss is from 5.4 to 9 d B.Due to the passive structure,the static power of the phase shifter is close to zero.Comparing with the reference,this design can keep a constant phase shift in a wider bandwidth with lower insertion loss and loss variation.