Double-Rate Tomlinson-Harashima Precoding for Multi-Valued Data Transmission

Abstract

SUMMARYThe growing demand for high-speed data communication has continued to meet the need for ever-increasing I/O bandwidth in recent VLSI systems. However, signal integrity issues, such as intersymbol interference (ISI) and reflections, make the channel band-limited at high-speed data rates. We propose high-speed data transmission techniques for VLSI systems using Tomlinson-Harashima precoding (THP). Because THP can eliminate ISI by inverting the characteristics of channels with limited peak and average power at the transmitter, it is suitable for implementing advanced low-voltage and high-speed VLSI systems. This paper presents a novel double-rate THP equalization technique especially intended for multi-valued data transmission to further improve THP performance. Simulation and measurement results show that the proposed THP equalization with a double sampling rate can enhance the data transition time and, therefore, improve the eye opening.

PAM-4 Eye-Opening Monitor Technique Using Gaussian Mixture Model for Adaptive Equalization

“…Although the FFE can suppress ISI, modifying the eye shape is challenging, especially when aiming to improve the complicated rising and falling edges of PAM-4 signals. Double-rate equalization employing fractional delay (T s /2) can expand the PAM-4 eye, and the eye shape can be more flexibly controlled compared with a conventional FFE by doubling the symbol rate [7]- [9]. However, the equalizer requires a high-speed operation that increases the hardware costs due to the implementation of high-frequency circuits.…”