Research On S-band Four-bit Digital Phase Shifting Technology

Phase shifter,an important component in phased array radar,changes the tilt angle of the lobes in an electronically controlled manner,replacing traditional mechanical rotation and improving the performance and efficiency of the radar.A phase shifter is also used in the communication base station,and the coverage area of the base station is increased by the electrically adjustable antenna,so that the utilization rate of the base station is further increased.In addition,phase shifters have applications in microwave measurement and power system power control.Low insertion loss,high phase accuracy,small size,large power capacity,and fast switching speeds are all directions that phase shifters need to develop.The thesis discusses the composition principle of PIN diodes,the working principle of forward bias and reverse bias,and corresponding equivalent circuits.Secondly,the working principles of several types of semiconductor phase shifters and their respective characteristics are described in detail.Finally,based on a PIN diode,a switch-line phase shifter structure is used to design an S-band four-digit digital phase shifter,and the power loss of the PIN diodes in several circuit topologies is compared and explained.At the same time,the design,simulation and debugging of each phase shifter unit are introduced in detail.The working frequency band of the four-phase phase shifter designed in this paper is 3.3GHz-3.8GHz.Finally,the performance meaurement of the fabricated phase shifter is completed.From the meaured results,we can know that the phase accuracy of the center frequency(3.55GHz)of the phase shifter is within ± 1°,the insertion loss is basically controlled below 1.5dB,and the input return loss and output return loss are basically better than 15 dB.