A DFE-Enhanced Phase-Difference Modulation Signaling for Multi-Drop Memory Interfaces

Abstract

This brief presents a phase-difference modulation signaling enhanced by decision feedback equalization for multi-drop memory interfaces. The phase-difference modulation signaling enables efficient data communication via a multi-drop channel, but only if the stub lengths are specially engineered. In this brief, the phase-difference modulation signaling is combined with decision feedback equalization to extend the applicable channel range. A test chip with a phase-difference-modulation transmitter and a decision feedback equalization receiver was fabricated in 65-nm CMOS technology. With a 2-tap decision feedback equalization, the test chip achieved the data rate of 7.8 Gb/s/pin via the both multi-drop channels with a long 10-cm stub and a short 2-cm stub, whereas the previous work without decision feedback equalization does not work with the 2-cm stub channel at 7.8Gb/s/pin.