A Ka band balanced amplifier with six-port power divider

In this paper for designing a Ka band balanced amplifier, a novel structure using a six-port power divider is proposed. Using this six-port power divider as a 3dB power divider and combiner, broadband properties and complete symmetric structure can be achieved. The symmetric structure leads to almost zero phase and gain unbalances between output ports of 3dB power dividers. In contrary to the conventional 3dB couplers, zero phase and gain unbalances of the proposed ones give nearly unity input and output VSWR in a balanced amplifier. If single amplifiers have grater bandwidth than the six-port power divider, there will be a critical instability problem in the balanced amplifier which utilizes six-port power divider. The problem was solved by inserting band pass filters in the power divider. So, using these band pass filters within the six-port power divider forms a novel balanced amplifier design which is proposed in this paper. The simulated and measured results are reported.