Why is the input common mode voltage (VICM) of the Arria II GX dedicated transceiver refclk pins lower than the 1.1V device specification?

Description

Due to a problem in the Quartus^® II software version 13.1 and earlier, the input common mode voltage (VICM) of the Arria^® II GX dedicated transceiver refclk pins with on-chip termination (OCT) enabled is 0.82V instead of 1.1V.

A VICM of 0.82v on the dedicated REFCLK pins will not cause any problems when your signal is AC coupled.

Resolution

This issue will be fixed in a future version of the Quartus^®  II software.