Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
18 years ago

LVDS I/O termination

Is an external 100Ohm resistor required at the input of an LVDS receiver I/O pair for the Cyclone III devices? The literature seems to suggest yes and no. Also, if I have "rx_in" as a single-channel ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
18 years ago

I agree, that the requirement of external differential termination may be not that obvious.

However, there is a figure 8–2. typical lvds application, that shows the external termination. The verbose discussion of transmitter termination networks is necessary because of the different handling in row and column banks.

If you are migrating from Cyclone or Cyclone II, you probably expect, that an external termination is necessary as with the predecessor, if you used Stratix before, you may expect an on-chip termination.