US Patent 10291193 Combining power amplifiers at millimeter wave frequencies

A system having a set of power amplifiers each having a primary inductive structure configured to provide an output signal. A secondary inductive structure is configured to inductively couple to each of the primary inductive structures. A transmission line is provided with a signal trace and a ground trace. The signal trace of the transmission line is connected to a first end of the secondary inductive structure. A return path from a second end of the secondary inductive structure is coupled via a resonant network to the ground trace of the transmission line, in which the return path is spaced away from the secondary inductive structure to minimize inductive coupling to the primary structures.