A Common-Mode Noise Suppression Filter for Gigahertz Differential Signals Based on Substrate Integrated Waveguide Resonators

Abstract

A common-mode noise suppression filter for microstrip differential lines based on substrate integrated waveguide resonator (SIWR) is proposed in this paper. The proposed common-mode filter (CMF) consists of cascaded SIWR units with different size. The equivalent characteristic impedance circuit model of the proposed CMF is given to predict the common-mode suppression characteristics by introducing the spectral domain approach (SDA). Simulated results show that the common-mode noise is decreased more than 35 dB from 4.5 GHz to 11.4 GHz, and-30 dB rejection band is obtained in the frequency band of 4.3-15 GHz. Moreover, the insertion loss and the group delay in the frequency domain show that there is little degradation for differential signals. In the time domain, 86.5% amplitude suppression of common-mode noise is achieved. In addition, the eye diagrams in the time domain are investigated to explain the effectiveness of the proposed CMF and indicate that the CMF can maintain the differential signal integrity. The prototype is fabricated to verify the validity of the proposed structure, and the measurement results show good agreement with the simulation results. INDEX TERMS Common-mode filter (CMF), high-speed differential signals, spectral domain approach (SDA), substrate integrated waveguide resonator (SIWR), signal integrity.

Design of a power supply protection circuit with EMI suppression function

“…They also have the ability to absorb electrostatic pulses.C1 and C2 are Y capacitors, and C3 is X capacitor, which are used to filter the power line at the front end of the circuit, eliminate differential mode interference and common mode interference on the power line, and reduce power noise. L5 is a common mode filter which is used to eliminate common mode noise at the back end of the circuit.C4 and C5 are Y capacitors which are used to eliminate differential mode noise at the back end of the circuit [6] .…”