Crosstalk-Aware Transmitter Pulse-Shaping for Parallel Chip-to-Chip Links

Crosstalk and inter-symbol interference are major obstacles towards increasing the data rate of chip-to-chip links. They are especially important in long, single-ended, parallel links. We find that when crosstalk is the dominant source of received noise, a transmitted pulse shape that combines slew-rate limiting with transmitter pre-emphasis is preferred. We present a framework for choosing a transmit pulse-shape that minimizes the combined effects of both crosstalk and inter-symbol interference. When implementing this optimal pulse shape, filter taps that are fractionally spaced are beneficial. As a test, various pulse shapes were injected into a test channel with three parallel microstrip lines, and the received eye diagrams were measured. The crosstalk-aware pulse shape results in an increased eye opening when compared to square and pre-emphasis pulses