An On-Chip Filter Using Near-End Cross-Coupling With Jigsaw Puzzle Shaped Resonators

In this paper, an on-chip band-pass filter with near-end cross-coupling (NECC) scheme is proposed based on the 0.13- $\mu \text{m}$ SiGe (Bi) CMOS processing technology. First, in order to increase the out-of-band suppression, the NECC is proposed to produce an extra transmission zero (TZ) without introducing extra resonators, thus increasing the out-of-band suppression. Then, in order to facilitate the design process, the jigsaw puzzle shaped resonator structure is proposed. This resonator consists of several teeth structure along the outer edge of the resonators. The proposed structure not only enhances the coupling coefficient at the same coupling width, but also the coupling coefficient can be flexibly tuned by modifying the outer teeth structure without changing the relative positions of the resonators. The proposed filter is theoretically analyzed, full-wave simulated, manufactured and measured. The measured results are generally in good agreement with the simulated results. The proposed filter can be applied in the unlicensed millimeter wave region of the 5G wireless communication systems.