Some problems about altera_pll on cyclone V device

Thank you and finally found the RREF_TL pin is unconnected. I think it may be the real reason.

--- Quote Start ---

did you check RREF_TL on your board?

from pin Connection Guide:

reference pins

RREF_TL Input - Reference resistor for transceiver and PLL

If any PLL, REFCLK pin, or transceiver channel is used, you must connect each RREF pin on that

side of the device through its own individual 2.0-kΩ +/- 1% resistor to GND. Otherwise, you may

connect each RREF pin on that side of the device directly to GND. In the PCB layout, the trace

from this pin to the resistor needs to be routed so that it avoids any aggressor signals.

--- Quote End ---