Heterogeneous integration (HI) is a rapidly developing field aimed at achieving high-density integration and miniaturization of devices for complex practical radio frequency (RF) applications. In this study, we present the design and implementation of two 3 dB directional couplers utilizing the broadside-coupling mechanism and silicon-based integrated passive device (IPD) technology. The type A coupler incorporates a defect ground structure (DGS) to enhance coupling, while type B employs wiggly-coupled lines to improve directivity. Measurement results demonstrate that type A achieves <-16.16 dB isolation and <-22.32 dB return loss with a relative bandwidth of 60.96% in the 6.5-12.2 GHz range, while type B achieves <-21.21 dB isolation and <-23.95 dB return loss in the first band at 7-13 GHz, <-22.17 dB isolation and <-19.67 dB return loss in the second band at 28-32.5 GHz, and <-12.79 dB isolation and <-17.02 dB return loss in the third band at 49.5-54.5 GHz. The proposed couplers are well suited for low cost, high performance system-on-package radio frequency front-end circuits in wireless communication systems.
Keywords: defective ground structure (DGS); directional couplers; integrated passive devices (IPD); wiggly lines.