AN 522: Implementing Bus LVDS Interface in Supported Intel® FPGA Device Families

ID 683803
Date 7/31/2018

Stub Termination

You must match the driver impedance to the stub characteristic impedance. Placing a series termination resistor RS at the driver output greatly reduces the adverse transmission line effect caused by long stub and fast edge rates. In addition, RS can be changed to attenuate the VID to meet the specification of the receiver.
Figure 21. Effect of Stub Termination (Driver in U1, Receiver in U2 and U10)This figure compares the VID at U2 and U10 when U1 is transmitting.