Novel Differential-Mode Equalizer With Broadband Common-Mode Filtering for Gb/s Differential-Signal Transmission

In high-speed differential signal transmission, signal integrity at the receiving end is mainly determined by high quality of the differential-mode signal and good suppression of the common-mode noise. In this paper, an innovative circuit with dual function of the differential-mode equalizer and common-mode filter (DME-CMF) is proposed. The differential-mode and common-mode characteristics of the proposed structure are discussed separately with their corresponding half-circuit model. Based on the proposed design methodology for the DME-CMF and the presented structure realizing the DME-CMF with a two-layer printed circuit board, a set of design parameters are determined for 8-Gb/s differential transmission and utilized in the fabrication of test boards. The frequency-domain and time-domain measurements of the test board successfully demonstrate the effectiveness of the proposed structure.