;In this study, miniature integrated dual-band microwave passive circuits are proposed. It provides a simple design method for miniaturization and dual-band operation. Conventional bridged-T coil replacing transmission line for miniaturization merely deals with single-band. Therefore, dual-band bridged-T coil is used to replace conventional bridged-T coil to design not only miniature but also dual-band microwave passive circuits. Here, miniature dual-band branch-line coupler and dual-behavior hybrid are realized by using dual-band bridged-T coil in Integrated Passive Device (IPD) and Gallium Arsenide (GaAs) processes. First, miniature dual-band branch-line couplers are presented. Operating frequencies of proposed circuits are at 2.45 GHz and 5.5 GHz. The electrical size of proposed circuit are around 0.018 λ0 × 0.011 λ0 at 2.45 GHz and 0.040 λ0 × 0.024 λ0 at 5.5 GHz. Second, miniature dual-band dual-behavior hybrid is presented. Operating frequencies of proposed circuits are at 2.45 GHz and 5.5 GHz. The electrical size of proposed circuit are around 0.025 λ0 × 0.025 λ0 at 2.45 GHz and 0.056 λ0 × 0.055 λ0 at 5.5 GHz. All of dual-band microwave passive circuits mentioned previously are undersized than the existing literatures. A novel dual-behavior hybrid with distinct responses in two operating bands is also presented. It proves that dual-band bridged-T coil can replace the transmission line and miniaturize microwave passive circuit size. In addition, it can reduce the complexity of dual-band or dual-band dual-behavior microwave passive circuits.
