Design Of Digital Phase Shifter In Phased Array Radar

T/R module is an important part of phased array radar,including low noise amplifier(LNA),power amplifier(PA),attenuators,RF switches,phase shifters and so on.As one of the most important parts,the performance of phase shifter will directly affect the whole system.Phase shifter abroad is more mature than the domestic both in technology and in process.High stability,high reliability and low cost gradually become the development trend of phase shifter.This paper introduces two different digital phase shifters of X band.They show good performance.At first,the background and significance of phase shifter in T / R module are briefly addressed and the principle of passive switching device is described as a selection of MOSFET switch control devices,then various frame shift characteristics and working principle of the structure of phase detector,compared to switched-line phase shifter,loaded line phase shifter and high-low-pass phase shifters are analyzed.The smaller degree of phase shifting unit uses a low-pass structure.The phase shifting unit with a large degree of the network structure use high-low-pass phase shifters to achieve phase shift state,it can be achieved flat frequency response within a given bandwidth and good performance.This design uses UMC0.18?m CMOS process and IBM 0.18?m BiCMOS process to simulate layout and taped,using Cadence software for designing.The circuit uses 5 phase shifting units,namely 11.25 °,22.5 °,45 °,90 °,180 °.Phase shift achieve 32 kinds of states in step of 11.25 °.The simulation shows,within the operating band from 9.4GHz to 10.6 GHz,the bandwidth of 1.2GHz,the insertion loss is 14 d B,amplitude fluctuation is 0.5dB,the phase shifting precision is 5 °,reach the design requirements.