Wave Synthesis Of High-power Amplifier Technology Research

In the system of microwave and millimeter-wave frequencies, the key transmitting ability of wireless transmitters depends on the output power of the high-power amplifiers at the end of system. However, the output power of each monolithic microwave integrated circuit (MMIC) PA is quite low, especially at millimeter-wave frequencies. Then, it's necessary to utilize power combining to achieve higher output-power of systems.This paper has discussed complication which can affect the combining efficiency, and has researched several methods of power combining. By using Millimeter-wave special power combining and circuit-level power combining, a modular approach based on high-power sub-module, which contains branched-waveguide coupler, waveguide-to-microstrip double probes and Wilkinson bridge, has utilized to be an amplification unit of N-cascade branched-waveguide coupler to design high-power PA. The technical problem of multiple-way high power combining has been solved successfully. Even and odd mode theory has been used to analyze branched-waveguide coupler. The electromagnetic field of the waveguide-microstrip face-to-face double probes has been analyzed deeply. Even and odd mode theory has been used to analyze Wilkinson bridge. Wilkinson bridge based on films resistor has been applied in millimeter-wave power combining field.Based on the researching and experimenting, the high-power sub-module amplifier with 8 TGA4517 MMICs can provide output power more than 44dBm(25W) from 30.5 GHz to 36 GHz, and more than 42.8dBm (18W) from 30GHz to 37.5GHz, and the highest power with 46.2dBm(41.7W) at 32.5GHz. The combining efficiency from 31 GHz to 37 GHz is 79.4%-83.2%.A 16-way power splitter/combiner has been produced with insertion loss 2.2-3.0dB. The combing loss of the combiner is about 0.9-1.2dB, which means the power-combining efficiency is 76%-81%.A 32-way power splitter/combiner has been produced with insertion loss 2.7-3.3dB. The combing loss of the combiner is about 1.2-1.5dB, which means the power-combining efficiency is 71%-76%.