IRWIN AND JOAN JACOBS CENTER FOR COMMUNICATION AND INFORMATION TECHNOLOGIES Parallel vs. Serial On-Chip Communication

Synchronous parallel links are widely used in modern VLSI designs for on-chip inter-module communication. Long range parallel links occupy large area and incur high capacitive load, high leakage power and cross-coupling noise. The problems exacerbate for applications having low utilization of the links or suffer from congestion of the interconnect. While standard synchronous serial links are unattractive due to limited bit-rate, novel high performance serial links may change the balance. In this paper we show that novel serial links provide better performance than parallel links for long range communications, beyond several millimeters. We analyze the technology dependence of link performance. An example for 65 nm technology is presented, and compare wavepipelined and register-pipelined parallel links to a high performance serial link in terms of bit-rate, power, area and latency.