High Isolation Integrated Passive Micro-Diplexer with Low Loss for Mobile Communication Applications

In this paper, a high isolation and low loss integrated passive micro-diplexer is designed through different combinations of inductors and capacitors. The design of the micro-diplexer uses the structure of a toroidal inductor and a metal-dielectric-metal type capacitor, and an air bridge structure is arranged at the port of the toroidal inductor. The air bridge structure is composed of multiple layers of metal and it provides a new way for the parallel connection of the inductor and the capacitor, which reduces the size of the micro-diplexer and improves the integration of the micro-diplexer. The proposed micro-diplexer realizes high-isolation communication and low-loss signal transmission at the operating frequency of 0.900 GHz and 1.800 GHz, respectively. And the insertion losses are 0.003 dB and 0.001 dB, the isolation degrees are 39.439 dB and 43.197 dB, respectively. In summary, the proposed micro-diplexer can be easily integrated with other devices through bond-wires, which is beneficial to improve the integration of radio frequency circuits. Moreover, it provides an effective solution for electronic devices to share a common communication channel, which is helpful to promote the exploration and application of micro-diplexer in duplex communication.