Synthesis Model and Design of a Common-Mode Bandstop Filter (CM-BSF) With an All-Pass Characteristic for High-Speed Differential Signals

A new common-mode bandstop filter (CM-BSF) with an all-pass performance (from dc to 9 GHz) for differential signals is proposed by using a C-shaped patterned ground structure (PGS) with meandered signal lines on a two-layer printed circuit board (PCB). This technique can successfully generate two close transmission zeros in common-mode within the frequencies of concern. A corresponding equivalent circuit model is established to predict the filter behaviors, and a formula for common-mode transmission zeros is derived based on the circuit model. Next, a design method is developed and a synthesis procedure is proposed. According to the procedure, a wideband CM-BSF is synthesized and fabricated on a two-layer PCB. In addition, the simulation and experiment results are demonstrated to verify the technique and show excellent performance of the proposed CM-BSF. It is shown that common-mode noise can be suppressed over 10 dB from 1.9 to 8.9 GHz with 130% fractional bandwidth (FBW) while the insertion loss of differential-mode can be kept less than 3 dB from dc to 9 GHz. The electrical size is only 0.21 λg ×0.21 λg, where λg is the wavelength of the stopband central frequency. To sum up, the proposed CM-BSF has merits of low cost (two layer), a simple geometric structure, a compact size, and a large common-mode FBW. Most importantly, the filter can keep good signal integrity of the digital differential signals due to its all-pass characteristic.

[1]  Kye Yak See,et al.  In-Circuit Characterization of Common-Mode Chokes , 2007, IEEE Transactions on Electromagnetic Compatibility.

[2]  Chi-Hsueh Wang,et al.  Balanced Coupled-Resonator Bandpass Filters Using Multisection Resonators for Common-Mode Suppression and Stopband Extension , 2007, IEEE Transactions on Microwave Theory and Techniques.

[3]  Makoto Takamiya,et al.  for High-Speed Digital Designs , 2004 .

[4]  Wenquan Che,et al.  Novel Wideband Differential Bandpass Filters Based on T-Shaped Structure , 2012, IEEE Transactions on Microwave Theory and Techniques.

[5]  Ferran Martin,et al.  Split rings-based differential transmission lines with common-mode suppression , 2011, 2011 IEEE MTT-S International Microwave Symposium.

[6]  Y. Miura,et al.  A new wideband common-mode noise filter consisting of Mn-Zn ferrite core and copper/polyimide tape wound coil , 2005, IEEE Transactions on Magnetics.

[7]  Quan Xue,et al.  A Novel Ultra-Wideband Differential Filter Based on Double-Sided Parallel-Strip Line , 2010, IEEE Microwave and Wireless Components Letters.

[8]  Clayton R. Paul.  A comparison of the contributions of common-mode and differential-mode currents in radiated emissions , 1989 .

[9]  Lin-Kun Wu,et al.  Design of miniaturized common-mode filter by multilayer low-temperature co-fired ceramic , 2004, IEEE Transactions on Electromagnetic Compatibility.

[10]  T. B. Lim,et al.  A Differential-Mode Wideband Bandpass Filter on Microstrip Line for UWB Application , 2009, IEEE Microwave and Wireless Components Letters.

[11]  T. Itoh,et al.  A Novel Wideband Common-Mode Suppression Filter for Gigahertz Differential Signals Using Coupled Patterned Ground Structure , 2009, IEEE Transactions on Microwave Theory and Techniques.

[12]  F. Medina,et al.  Differential Bandpass Filter With Common-Mode Suppression Based on Open Split Ring Resonators and Open Complementary Split Ring Resonators , 2013, IEEE Microwave and Wireless Components Letters.

[13]  Lin-Kun Wu,et al.  Design of miniaturized common-mode filter by multi-layer low temperature co-fired ceramic , 2003 .

[14]  F. Medina,et al.  Common-Mode Suppression in Microstrip Differential Lines by Means of Complementary Split Ring Resonators: Theory and Applications , 2012, IEEE Transactions on Microwave Theory and Techniques.

[15]  Quan Xue,et al.  Novel Balanced Dual-Band Bandpass Filter Using Coupled Stepped-Impedance Resonators , 2010, IEEE Microwave and Wireless Components Letters.

[16]  Tzong-Lin Wu,et al.  A Broadband and Miniaturized Common-Mode Filter for Gigahertz Differential Signals Based on Negative-Permittivity Metamaterials , 2010, IEEE Transactions on Microwave Theory and Techniques.

[17]  Tzong-Lin Wu,et al.  Radiation Suppression for Cable-Attached Packages Utilizing a Compact Embedded Common-Mode Filter , 2012, IEEE Transactions on Components, Packaging and Manufacturing Technology.

[18]  Tzong-Lin Wu,et al.  An Embedded Common-Mode Suppression Filter for GHz Differential Signals Using Periodic Defected Ground Plane , 2008, IEEE Microwave and Wireless Components Letters.

[19]  Lei Zhu,et al.  Highly Selective Differential-Mode Wideband Bandpass Filter for UWB Application , 2011, IEEE Microwave and Wireless Components Letters.

[20]  Chi-Hsueh Wang,et al.  Stopband-Extended Balanced Bandpass Filter Using Coupled Stepped-Impedance Resonators , 2007, IEEE Microwave and Wireless Components Letters.

[21]  J. D. Gavenda.  Measured effectiveness of a toroid choke in reducing common-mode current , 1989, National Symposium on Electromagnetic Compatibility.