Line Coding Techniques for Channel Equalization: Integrated Pulse-Width Modulation and Consecutive Digit Chopping

This paper presents two new line-coding schemes, integrated pulse width modulation (iPWM) and consecutive digit chopping (CDC) for equalizing lossy wireline channels with the aim of achieving energy efficient wireline communication. The proposed technology friendly encoding schemes are able to overcome the fundamental limitations imposed by Manchester or pulse-width modulation encoding on high-speed wireline transceivers. A highly digital encoder architecture is leveraged to implement the proposed iPWM and CDC encoding. Energy-efficient operation of the proposed encoding is demonstrated on a high-speed wireline transceiver that can operate from 10 to 18 Gb/s. Fabricated in a 65-nm CMOS process, the transceiver operates with supply voltages of 0.9 V, 1 V, and 1.1 V. With the help of the proposed iPWM encoding, the transceiver can equalize over 27-dB of channel loss while operating at 16 Gb/s with an efficiency of 4.37 pJ/bit. The design occupies an active die area of 0.21 mm².