Miniaturized Low‐Loss Diplexer Based on Modified Topology Using Si‐Based IPD Technology

ABSTRACT In this letter, a miniaturized low‐loss diplexer based on a modified topology and implemented in silicon‐based integrated passive device (IPD) technology is proposed. The modified topology consists of a low‐pass channel and a band‐pass channel. By analyzing the transmission zero generation mechanisms in both passbands, high frequency selectivity is achieved. To verify the proposed design, a prototype with dimensions of 1.6 × 0.8 × 0.25 mm is fabricated using silicon‐based IPD technology. Measured results demonstrate that the proposed diplexer exhibits an insertion loss less than 0.6 dB and isolation better than 20 dB in the 0.66–0.94 GHz band, while achieving an insertion loss less than 0.7 dB and isolation better than 16 dB in the 1.69–2.73 GHz band. Compared with previously reported diplexer designs, the proposed work achieves favorable performance in terms of miniaturization and insertion loss.