Design and Implementation of New 3-dB Quadrature Couplers Using PCB and Silicon-Based IPD Technologies

In this paper, new 3-dB quadrature couplers based on the two-layered edge-coupling mechanism are designed and implemented in the printed circuit board (PCB) and silicon-based integrated passive device (IPD) technologies. To achieve strong edge-coupling, the proposed coupler consists of two sets of parallel-connected lines, which are placed on the top and bottom metallic layers of the substrate slab, respectively. The design concept and procedures are first exemplified by implementing a 3-dB coupler in the PCB technology at 2 GHz. In addition, since the proposed circuit structure avoids using bonding wires or air bridges, it has the advantage of applying in the millimeterwave range. However, as the proposed coupler designed in the multilayered IPD substrate, it will lead to an obvious phase velocity difference between two orthogonal modes, c and π-mode waves. To compensate this phenomenon, two millimeter-wave IPD couplers with different slow-wave structures are proposed, designed, and experimentally verified at 38 GHz.