Design of Single-Turn Spiral Inductors With Embedding A Strong-Coupling LC Resonator for Interference Suppression

This paper presents a study on the interference suppression effect of a resonator-embedded spiral inductor topology. In the proposed topology, a conventional single-turn spiral inductor is integrated with an embedded strong coupling LC resonator on a printed circuit board. This LC resonator can be designed with a specific resonant frequency near but below the operation band to achieve interference suppression by way of redirecting the magnetic flux emitted from the spiral inductor to the resonator, rather than toward the other spiral inductors outside around. In this paper, the design of interference suppression is mainly demonstrated at the LTE 700-MHz band. From the experimental results in a contrast case, the interference at 700 MHz can be depressed more than 20 dB by the proposed topology as referred to a conventional spiral inductor. The proposed topology can provide a design freedom in any interested frequency bands, such as the popular GSM bands (900/1800 MHz) or ISM bands (2.4 GHz), by changing the capacitance value of the resonator. To verify the interference suppression effect resulted from the proposed topology, electromagnetic simulations and experimental measurements in both frequency domain and time domain are conducted to provide the more in-depth view.