Globally Wireless Locally Wired (GloWiLoW): A Clock Distribution Network for Many-Core Systems

Modern high-performance systems are now facing critical issues on delivering power-efficient and globally interconnected clock networks. Conventional metal-based interconnect has gradually reached its bottleneck with the technology scaling which limits system performance as the interconnect delay has already overweighed circuit gate delay. A typical clock distribution network (CDN) might consume up to 50% of the total chip power and could generate large phase delay and clock uncertainties due to its RC characteristic and unbalanced load. This paper proposes a novel hybrid wire-wireless CDN, which improves the performance of on-chip clock distribution significantly using embedded wireless clock transmitter and receiver fabrics. In particular, On-Off-Keying (OOK) transceivers are implemented for overall system simplicity and has achieved significant power-efficiency. Results indicate that the total propagation delay can be reduced to 39.4ps, which is 57 times lower than the conventional H-tree. Besides, the system clock skew can be predictable and limited only by the displacement of clock receivers. Less than 26.9ps of clock skew (6.7% of a clock period at 2.5GHz) could be found within the proposed CDN and hence, shows the promising potential of future high-performance on-chip clock distribution.