Julian Ferry, High Speed Engineering Manager, Samtec
O. J. Danzy, Marketing, Agilent
Jim Nadolny, Senior SI and EMI Specialist, Samtec
Mike Resso, Product Manager, Signal Integrity Applications, Agilent

Today’s telecommunication systems are undergoing tremendous change due to demands on bandwidth requirements. The triple play of voice, video, and data demand high-performance systems with optimized backplanes and interconnects. To achieve high speeds, new protocols are emerging that break from the traditional 100 Ohm differential circuit architecture. New 75 Ohm single-ended and 85 Ohm differential topologies have been proposed to enable higher data rates, but care must be taken to avoid channel simulation errors caused by mixed reference impedances of cascaded S-parameter blocks. This paper critically examines various test and measurement methodologies to provide unique insight into characterizing non-standard impedance designs.