Why does the rx_freqlocked signal get stuck high for an Rx only transceiver instances in Cyclone® IV GX devices?

Description

You may see the rx_freqlocked signal get stuck high for an Rx only transceiver instance due to a bug in Quartus® II software versions 12.0 SP2 and earlier software.

Resolution

To fix this problem in Quartus II 12.0 SP2 install patch 

• Quartus II software version 12.0 SP2 patch 2.07 for Windows (.exe)
• Quartus II software version 12.0 SP2 patch 2.07 for Linux (.tar)
• Quartus II software version 12.0 SP2 patch 2.07 ReadMe file (.txt)

This issue will be fixed in a future version of the Quartus II Software.