Millimeter-wave Solid-state Power Combining Technology Research

With the rapid development of the satellite communications, electronic warfare systems and phased array radar, larger output power of millimeter-wave system have becoming demanded increasingly. Large output power means more communication distance and greater anti-interference capability. Since the output power of a single solid-state device is limited, the power synthesis technology is demanded.This paper studies in-depth power splitters for example waveguide E-T junction, branch-waveguide coupler, Magic-T waveguide etc, and carries out modeling and optimizes employing electromagnetic simulation software CST and HFSS, analyzes the advantages and disadvantages of various power splitters. We have designed eight-way power divider/combiner network comprehensive utilization of both low insertion loss of E-T waveguide junction and high isolation of the branch waveguide directional coupler. According to the requirements of the engineer design we analysis and simulate microstrip-to-waveguide probe transition, waveguide-to-microstrip antipodal finline transition. In addition, we have discussed the main factors that affect the combining efficiency of power amplifier.On the basis of the above works, we designs a two-stage driver amplifier module and power synthesis amplifier module, each level module is produced individually, attenuation chip is added to the driver stage amplifier module used for controlling automatic gain and adjusting the stepper, input port and output port of the system have joined detector used to monitor the input and output signal power. Finally, eight-way power combining amplifier is produced on the basis of the eight-way power divider/combiner network adopting TGA-4505 high-power MMIC chips, putting a separate power chip into a cavity to form a power amplifier module, the various modules exist independently with each other. Finally, layout of power divider/combiner network topology is creatively designed, the driver stage amplifier module, input/output detection circuit are placed on the same chamber with novel structure. It has easy maintenance, high reliability and easy expansion characteristics. Finally, we achieve the negative pressure protection, automatic gain control, step control functions using a microcontroller control circuit offered by a company. It has been tested that the synthetic power is greater than 43.4dBm during the whole work band, maximum synthetic efficiency has reached 90 percent. The system also has the performance of excellent heat-sink and favorable value in engineering applications.