Miniaturized Low-Loss and Wideband Diplexer With Mixed Stacked Inductors Using Dual-RDL TGV Technology

In this letter, a miniaturized low-loss and wideband diplexer with mixed stacked inductors is proposed using the Dual-redistribution layer (dual-RDL) glass-based advanced packaging technology. The mixed using the 3-D stacked high-<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> inductors and 2-D planar gradient inductors is introduced in the proposed diplexer for low insertion loss and compact chip size. Furthermore, a modified circuit topology is presented, which can generate multiple transmission zeros (TZs) outside of the two passbands. The proposed diplexer is realized using through glass via (TGV) technology and measuring with ground-source–ground (GSG) probe. From the measured results, it can achieve an insertion loss of less than 0.85 and 0.62 dB, and the isolation is better than 21.5 dB in the two operating bands (0.25–0.95 GHz and 1.71–2.69GHz). In particular, the proposed diplexer can achieve the wideband performance, and the measured fractional bandwidth (FBW) of the two passbands is 116.7% and 44.5%. Also, this design occupies an area of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.6\times 0.8$</tex-math> </inline-formula> mm. In comparison with the previously reported designs, the proposed diplexer shows the superior advantages of smaller size, wideband, and lower insertion loss. The simulation and measured results show good consistency.