An Analytical Design Approach of T-Section Passive Equalizer for High-Speed Digital Signal Transmissions Using Metal Cables

Abstract

In this paper, an analysis design method of T-shape passive equalizer circuits for high-speed digital cable transmission is proposed. The design is based on the fact that the circuit constant is uniquely determined by the DC value of the transfer function and the frequency where the transfer function is the square root of the DC value. This design method was applied to a 3.125 Gbps digital signal transmission of a 10 m long differential cable, and the validity of the method is confirmed since the transmission characteristics of the equalizer and the cable were constant in a range of ±1 dB in a signal band of 1.25 GHz. Furthermore, the effectiveness of the method was proved, since the value of the transmission characteristic measured with an evaluation circuit board was as designed and total jitter was suppressed under the XAUI standard using the eye pattern evaluation.