An Isolated RF Power Combining Approach with Multiple Decoupled Input Coils

To meet high RF power levels, it is common to combine the output power from multiple power amplifiers. Conventional isolated power combining networks are bulky and inefficient, while efficient lossless combiners lack necessary isolation for industrial applications. In this paper, an isolated RF power combining approach is proposed. A polygonal coupling coil structure is further proposed, which can allow an arbitrary number of input ports while eliminating cross-coupling between them by flux cancellation. A capacitor decoupling network is also introduced to further improve decoupling performance at high frequencies. The proposed system maintains ZVS operation of all amplifiers with mismatched gate signals. An experimental prototype with compact isolation coupler of 10cm×10cm×1.3cm is demonstrated, which combines four 13.56MHz Class-E power amplifiers and outputs 50W-300W power with a stable efficiency of 65%.