Design of Miniaturized On-Chip Bandpass Filters Using Inverting-Coupled Inductors in (Bi)-CMOS Technology
In this work, a new type of miniaturized on-chip resonator using coupled-inductor structure is presented. The impact on resonances of the structure due to the use of non- inverting- and inverting-coupled configuration is extensively investigated. It has been found that using the inverting-coupled structure, a stronger resonance can be generated, which is ideally suitable for device miniaturization. To fully understand the working mechanism of the resonator and use it effectively for bandpass filter (BPF) design, simplified LC equivalent-circuit models and detailed theoretical analysis are provided. To further demonstrate the proposed concept is useful in practice, not only a 1st-order BPF, but also another two 2nd-order BPFs are designed and fabricated in a standard 0.13-μm (Bi)-CMOS technology. All of them are designed to have a centre frequency around 15 GHz. Their physical dimensions are 0.13 x 0.25 mm², 0.26 x 0.25 mm², 0.24 x 0.22 mm², respectively. Good agreements between simulation and measurement have been obtained, which verify that the presented design approach is suitable for miniaturized on-chip passive design.