A Synthesized Method for Common-Mode Noise Suppression Filters With Specified Common-Mode and Differential Mode Response

In this paper, a synthesized method for broad-band lumped-element-based common-mode noise suppression filter (CMNSF) is proposed. Such CMNSF can achieve theoretically lossless performance and controllable dispersive group delay response for differential signals. Besides, the proposed CMNSF can achieve two common-mode transmission zeros, and both frequencies can be arbitrarily assigned to strengthen the suppression ability at certain bands. To validate the synthesized method, a CMNSF with fourth-order equiripple group delay response is demonstrated and validated in an integrated passive device process. The filter can suppress the common-mode noise more than 10 dB from 1.92 to 5.02 GHz or more than 20 dB from 2.20 to 4.20 GHz. At the same time, differential insertion loss is kept less than 3 dB up to 15 GHz and the group delay is kept in a +/- 5% error up to 12 GHz, which is widest one compared to the published works. In addition, the occupied area with probing pads is 1047 mu m x 954 mu m, which is compatible to previous works. Therefore, the proposed method is suitable for implementing a lumped-element-based CMNSF with ultraflattened group delay for differential signals based on nonferrite material.