The LVPECL input standard is supported by the LVDS differential input buffer. LVPECL inputs can be implemented by instantiating a ILVDS buffer in your RTL source code.
The LVPECL output standard is emulated using complementary LVCMOS outputs in conjunction with a parallel resistor across the driver outputs.
See figure 3-3.Differential LVPECL33 in the
LatticeECP3 datasheet for more information on the external circuitry needed to emulate the LVPECL outputs.
For further information on utilizing the sysI/O buffer to support a variety of standards please see
TN1177 LatticeECP3 sysI/O Usage Guide