LAUSR

A novel quad-mode common-mode filter (CMF) with ultra-wideband and high common-mode (CM) rejection-level is proposed based on the asymmetric short-stub loaded resonator (ASSLR). By utilizing the ASSLR, four resonant modes can be introduced for the initial CMF design under the even-mode operation, and correspondingly generate four CM transmission zeros. However, the initial CMF design achieves a weak CM noise suppression performance. Then, the CMF using the modified ASSLR is proposed for CM stopband enhancement. Finally, a surface mounted packaging CMF prototype is fabricated with the physical size of 6mm $\times 4.5$ mm $\times 0.6$ mm by using low-temperature co-fired ceramic (LTCC) technology. The measured results agree well with the simulated ones. The proposed quad-mode CMF exhibits excellent performances including high differential-mode cutoff frequency (10GHz), and an ultra-wide −15dB CM stopband with a fractional bandwidth of 104.5%.