9.4.7 Termination Resistor

As shown earlier, an LVDS communication channel employs a current source driving a transmission line that is terminated with a resistive load. This load serves to convert the transmitted current into a voltage at the receiver input. To ensure incident wave switching (which is necessary to operate the channel at the highest signaling rate), the termination resistance should be matched to the characteristic impedance of the transmission line. The designer should ensure that the termination resistance is within 10% of the nominal media characteristic impedance. If the transmission line is targeted for 100-Ω impedance, the termination resistance should be between 90 Ω and 110 Ω.

The line termination resistance should be placed as close to the receiver as possible to minimize the stub length from the resistor to the receiver.

Remember to only place line termination resistors at the end(s) of the transmission line in these multidrop topologies.