Modeling and design optimization of a wide-band passive equalizer and hybrid equalizer based on near-end crosstalk (NEXT) and reflections for high-speed serial links

Abstract

In recent years, the data rates of serial chip-to-chip digital I/O communication channels have increased considerably and are now over 10 Gb/s. Due to these increasing data rates, high-speed digital I/O signals are seriously suffering from frequency-dependent losses on printed circuit boards (PCBs) and at cables, consequently resulting in inter-symbol interference (ISI) problems and the subsequent degradation of receiver eye-opening, timing jitter, and voltage margin with declined system sensitivity and bit-error-rate (BER). In order to compensate for the frequency-dependent losses in a high-speed I/O channel, equalization methods have received significant attention as practical loss-compensation techniques for transmitter and receiver designs. Among various equalization methods, on-chip active equalization is a beneficial approach for applications that require active gain. However, on-chip active equalization inevitably sacrifices active power consumption and suffers from bandwidth limitation with current IC technology. On the other hand, passive equalization techniques are preferred for applications with low power consumption or with a wide bandwidth requirement. However, to achieve wide band in passive equalization, costly materials and manufacturing processes are required for wide-band passive component implementation. Even though wide band is achieved, it still has a DC attenuation problem, which is an inherent drawback of passive equalizers. In this thesis, a sophisticated wide-band passive equalization technique using microwave effects is proposed, which can be easily integrated on a planar package and PCB with conventional manufacturing processes. The newly proposed passive equalizer consists of coupled microstrip line structures with different characteristic impedances, which intentionally cause near-end crosstalk (NEXT) and reflections as the main mechanisms for pre-emphasis and de-emphasis, respectively. An analytic model and an equivalent circuit...