Package level interconnect options

Abstract

Scaling enhances intrinsic transistor performance and degrades interconnects. As the technology steps into nanometer era, global interconnects are becoming bottleneck for overall chip performance. In this paper, we show package level interconnects are an effective alternative for on-chip global wiring. These interconnects behave as LC transmission lines and can be exploited for their near speed of light transmission and low attenuation characteristics. We compare performancebandwidth, bandwidth density, latency and power consumptionof the package level transmission lines with conventional on-chip global interconnects for different ITRS technology nodes. Based on these results, we show package level interconnects are well suited for power demanding low latency applications and we analyze different interconnect options like memory buses, long inter tile interconnects, clock and power distribution.

Constant impedance scaling paradigm for interconnect synthesis

“…The LC transmission lines are reverse scaled metal interconnects that behave essentially like a wave-guide with the signals propagating at near speed of light [10,11]. The delay of the LC transmission lines are inherently linear in length and don't necessitate repeaters.…”

“…Benefits of the LC transmission line interconnect for large L2 cache memory application is discussed in [12]. In [11], it was shown that the LC transmission lines offer 3-7x improvement in bandwidth with as much as 75% saving in power over conventional global interconnects. With a prototype, [13] showed advantages of clock distribution with the LC transmission lines.…”

Analysis and Modeling of Power Grid Transmission lines

“…The (LC) transmission lines are well suited for high quality intra-chip signal transmission at multi gigabit data rates. In [2] it was shown that transmission lines compared to conventional global (RC) interconnects offer superior bandwidth, latency and power characteristics. Benefits of transmission lines for on-chip cache applications are discussed in [3].…”

“…However a disadvantage of the transmission line approach is it's poor wiring density [2,3]. The transmission lines not only require fat metal wires but also need good return paths.…”