A passive differential termination and signal sensing device for high-speed (40 Gb/s) test applications

Differential inputouput buffers are frequently utilized in high-speed communication systems. Often, a transmit buffer is connected to a 100-\Omega differential receive buffer through a passive interconnect link with no means of verifying the true differential signal quality of the transmitter. Additionally, many electrical protocol specifications are defined assuming differential transmitter termination into 100 \Omega with no common-mode reference. Commercially available, active probe test equipment can be cost prohibitive or have limited functionality due to unwanted parasitics inherent in the active devices. This paper describes a passive high-bandwidth 100- \Omega differential termination device for characterizing high-speed differential buffers using standard test equipment.