GHz clock distribution circuit in Si ULSI: comparison of distributed RC line and transmission line

摘要

According to conventional circuit theory, transmission lines should be used when transmitting GHz clock signals on cm-order long global interconnect in a LSI. However until now, such long interconnects have been broken up into smaller lengths using CMOS repeaters, so that they can be treated as distributed RC lines instead. Nevertheless, with ever increasing clock frequencies and interconnect lengths, more repeaters will become necessary, and they will result in higher power dissipation and delay times. In this work, we have compared the distributed RC line and the transmission line in terms of power dissipation and delay time using PSpice simulation, and found that transmission lines are more suitable for transmission of GHz signals on cm-order long interconnects.