Dual-Band High Absorbing and Broadband Suppressing Common-Mode Noise Filter

In this article, a common-mode noise filter with a wideband suppressing and dual-band high absorbing common mode filter, which is called absorptive common-mode filter, is proposed. The filter is constructed by a reflective-type common-mode filter, a phase matching, and an absorber. It is composed of three layers with 14.98 mm × 9.585 mm. The broadband common-mode noise suppression can be achieved by positioning multiple transmission zeros. By using dual-band phase matching and an absorber, the dual-band absorption can be realized. The frequencies are in the range of 2.4 to 2.5 GHz and 5.17 to 5.33 GHz, respectively. The positioning of transmission zeros and absorption points at those frequencies leads to a high absorption efficiency. The simulation result shows that the common-mode suppression, which is below −10 dB, is from 2 to 11 GHz. The fractional bandwidth is 138%. The differential-mode signal keeps integrity in the range from DC to 12 GHz. The absorption efficiencies in the two frequency sections are 97% and 96%, respectively. The experiment results show only slight differences from the simulation results.